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Jack Dorsey, CEO of Twitter during the annual Clinton Global Initiative (CGI) September 23, 2010 in New York . The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti.

Jack Dorsey, CEO of Twitter (L) and John Chambers, CEO of Cisco during the annual Clinton Global Initiative (CGI) September 23, 2010 in New York . The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti.

Jack Dorsey, CEO of Twitter (L) and John Chambers, CEO of Cisco attend the annual Clinton Global Initiative (CGI) September 23, 2010 in New York . The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti.

NEW YORK, NY - SEPTEMBER 23: Jack Dorsey, the Co-Founder and Chairman of Twitter, speaks at a press conference announcing the DNA Foundation's 'Real Men Don't Buy Girls' campaign against sexual slavery during the annual Clinton Global Initiative (CGI) on September 23, 2010 in New York City. The DNA Foundation was founded by the actors Ashton Kutcher and Demi Moore. The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti. The event, founded by Clinton after he left office, is held the same week as the General Assembly at the United Nations, when most world leaders are in New York City.

NEW YORK - OCTOBER 09: A view of the twitter pic room where guests can take a photo and upload to their accounts plus recieve a hard copy while they wait during the Redu project presented by Bing on October 9, 2010 in New York City.

A man looks at a computer monitor on October 14, 2010 displaying a web page with a photograph of an earthworm spotted by Tver region governor Dmitry Zelenin in his plate of salad during a reception for German President Christian Wulff and his wife at the Kremlin in Moscow. Zelenin, who posted the photo of the small red worm on his Twitter, was branded an 'imbecile' by the Kremlin. Later the governor deleted the posting.

WASHINGTON - OCTOBER 14: U.S. President Barack Obama talks with moderator Sway Calloway during a Town Hall on Viacom�s BET, CMT and MTV networks October 14, 2010 in Washington, DC. Obama appeared before approximately 250 young people representing a broad cross-section of backgrounds and answered questions from the studio audience as well as from viewers submitting questions via Twitter.

NEW YORK, NY - SEPTEMBER 23: Jack Dorsey, the Co-Founder and Chairman of Twitter, talks during a panel called 'Enhancing Access to Modern Technology' during the annual Clinton Global Initiative (CGI) on September 23, 2010 in New York City. The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti. The event, founded by Clinton after he left office, is held the same week as the General Assembly at the United Nations, when most world leaders are in New York City.

WASHINGTON - OCTOBER 14: U.S. President Barack Obama greets moderator Sway Calloway while participating in a Town Hall on Viacom�s BET, CMT and MTV networks October 14, 2010 in Washington, DC. Obama appeared before approximately 250 young people representing a broad cross-section of backgrounds and answered questions from the studio audience as well as from viewers submitting questions via Twitter.

NEW YORK, NY - SEPTEMBER 23: Jack Dorsey, the Co-Founder and Chairman of Twitter, talks during a panel called 'Enhancing Access to Modern Technology' during the annual Clinton Global Initiative (CGI) on September 23, 2010 in New York City. The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti. The event, founded by Clinton after he left office, is held the same week as the General Assembly at the United Nations, when most world leaders are in New York City.

Security personnel, including a plainclothes policeman in dark sunglasses (C), man the entrance way to home of China's Nobel Peace prize winner Liu Xiaobo in Beijing on October 11, 2010. Liu Xia, the wife of this year's Nobel Peace Prize winner Liu Xiaobo, said she is under house arrest at her home in Beijing and pleaded for help in broadcasting her plight. Posting on her Twitter account, she said she had just returned from visiting her husband in a northeastern China prison where she informed him of his award, but that she was now being detained incommunicado.

A plainclothes policeman in dark sunglasses speaks on his mobile phone beside the entrance to the home of China's Nobel Peace prize winner Liu Xiaobo in Beijing on October 11, 2010. Liu Xia, the wife of this year's Nobel Peace Prize winner Liu Xiaobo, said she is under house arrest at her home in Beijing and pleaded for help in broadcasting her plight. Posting on her Twitter account, she said she had just returned from visiting her husband in a northeastern China prison where she informed him of his award, but that she was now being detained incommunicado.

HAYDOCK, ENGLAND - NOVEMBER 20: Shane Byrne riding Stagecoach Pearl jump the last to win The Follow Paul Nicholls On Facebook And Twitter Handicap Steeple Chase as Richard Johnson falls from his mount My Moment at Haydock Park racecourse on November 20, 2010 in Haydock, England.

NEW YORK, NY - SEPTEMBER 23: Jack Dorsey, (C), the Co-Founder and Chairman of Twitter, walks off the stage after a press conference announcing the DNA Foundation's 'Real Men Don't Buy Girls' campaign against sexual slavery during the annual Clinton Global Initiative (CGI) on September 23, 2010 in New York City. The DNA Foundation was founded by the actors Ashton Kutcher and Demi Moore. The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti. The event, founded by Clinton after he left office, is held the same week as the General Assembly at the United Nations, when most world leaders are in New York City.

NEW YORK, NY - SEPTEMBER 23: Jack Dorsey, the Co-Founder and Chairman of Twitter, speaks at a press conference announcing the DNA Foundation's 'Real Men Don't Buy Girls' campaign against sexual slavery during the annual Clinton Global Initiative (CGI) on September 23, 2010 in New York City. The DNA Foundation was founded by the actors Ashton Kutcher and Demi Moore. The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti. The event, founded by Clinton after he left office, is held the same week as the General Assembly at the United Nations, when most world leaders are in New York City.

NEW YORK, NY - SEPTEMBER 23: Jack Dorsey, the Co-Founder and Chairman of Twitter, speaks at a press conference announcing the DNA Foundation's 'Real Men Don't Buy Girls' campaign against sexual slavery during the annual Clinton Global Initiative (CGI) on September 23, 2010 in New York City. The DNA Foundation was founded by the actors Ashton Kutcher and Demi Moore. The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti. The event, founded by Clinton after he left office, is held the same week as the General Assembly at the United Nations, when most world leaders are in New York City.

A man looks at a computer monitor desplaying a web page with a a photograph of an earthworm spotted by Tver region governor Dmitry Zelenin in his plate of salad at a Kremlin's reception, Moscow, on October 14, 2010. Zelenin, who posted a photograph of the small red worm on his Twitter, was branded an 'imbecile' by the Kremlin. Later the governor deleted the posting.

WASHINGTON - OCTOBER 14: U.S. President Barack Obama speaks during a Town Hall on Viacom�s BET, CMT and MTV networks October 14, 2010 in Washington, DC. Obama appeared before approximately 250 young people representing a broad cross-section of backgrounds and answered questions from the studio audience as well as from viewers submitting questions via Twitter.

WASHINGTON - OCTOBER 14: U.S. President Barack Obama talks with moderator Sway Calloway while participating in a Town Hall on Viacom�s BET, CMT and MTV networks October 14, 2010 in Washington, DC. Obama appeared before approximately 250 young people representing a broad cross-section of backgrounds and answered questions from the studio audience as well as from viewers submitting questions via Twitter.

HAYDOCK, ENGLAND - NOVEMBER 20: Shane Byrne riding Stagecoach Pearl jump the last to win The Follow Paul Nicholls On Facebook And Twitter Handicap Steeple Chase as Richard Johnson falls from his mount My Moment at Haydock Park racecourse on November 20, 2010 in Haydock, England.

WASHINGTON - OCTOBER 14: U.S. President Barack Obama greets moderator Sway Calloway while participating in a Town Hall on Viacom�s BET, CMT and MTV networks October 14, 2010 in Washington, DC. Obama appeared before approximately 250 young people representing a broad cross-section of backgrounds and answered questions from the studio audience as well as from viewers submitting questions via Twitter.

NEW YORK, NY - SEPTEMBER 23: Jack Dorsey, the Co-Founder and Chairman of Twitter, talks during a panel called 'Enhancing Access to Modern Technology' during the annual Clinton Global Initiative (CGI) on September 23, 2010 in New York City. The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti. The event, founded by Clinton after he left office, is held the same week as the General Assembly at the United Nations, when most world leaders are in New York City.

Security personnel, including a plainclothes policeman in dark sunglasses (C), man the entrance way to home of China's Nobel Peace prize winner Liu Xiaobo in Beijing on October 11, 2010. Liu Xia, the wife of this year's Nobel Peace Prize winner Liu Xiaobo, said she is under house arrest at her home in Beijing and pleaded for help in broadcasting her plight. Posting on her Twitter account, she said she had just returned from visiting her husband in a northeastern China prison where she informed him of his award, but that she was now being detained incommunicado.

NEW YORK, NY - SEPTEMBER 23: Jack Dorsey, the Co-Founder and Chairman of Twitter, talks during a panel called 'Enhancing Access to Modern Technology' during the annual Clinton Global Initiative (CGI) on September 23, 2010 in New York City. The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti. The event, founded by Clinton after he left office, is held the same week as the General Assembly at the United Nations, when most world leaders are in New York City.

WASHINGTON - OCTOBER 14: U.S. President Barack Obama greets moderator Sway Calloway while participating in a Town Hall on Viacom�s BET, CMT and MTV networks October 14, 2010 in Washington, DC. Obama appeared before approximately 250 young people representing a broad cross-section of backgrounds and answered questions from the studio audience as well as from viewers submitting questions via Twitter.

Supporters of Brazilian presidential candidate for the ruling Workers Party, Dilma Rousseff, receive a class on how to use Twitter and other Internet tools to spread information about the candidate in Porto Alegre, southern Brazil, on October 15, 2010. Rousseff and Jose Serra, of the Brazilian Social Democratic Party (PSDB), will face each other on October 31 in the run-off election.

Supporters of Brazilian presidential candidate for the ruling Workers Party, Dilma Rousseff, receive a class on how to use Twitter and other Internet tools to spread information about the candidate in Porto Alegre, southern Brazil, on October 15, 2010. Rousseff and Jose Serra, of the Brazilian Social Democratic Party (PSDB), will face each other on October 31 in the run-off election.

NEW YORK, NY - SEPTEMBER 23: Jack Dorsey, the Co-Founder and Chairman of Twitter, listens during a panel called 'Enhancing Access to Modern Technology' during the annual Clinton Global Initiative (CGI) on September 23, 2010 in New York City. The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti. The event, founded by Clinton after he left office, is held the same week as the General Assembly at the United Nations, when most world leaders are in New York City.

NEW YORK, NY - SEPTEMBER 23: Jack Dorsey, (C), the Co-Founder and Chairman of Twitter, and Pamela Passman, the Vice President of Global Corporate Affairs for Microsoft, walks off the stage after a press conference announcing the DNA Foundation's 'Real Men Don't Buy Girls' campaign against sexual slavery during the annual Clinton Global Initiative (CGI) on September 23, 2010 in New York City. The DNA Foundation was founded by the actors Ashton Kutcher and Demi Moore. The sixth annual meeting of the CGI gathers prominent individuals in politics, business, science, academics, religion and entertainment to discuss global issues such as climate change and the reconstruction of Haiti. The event, founded by Clinton after he left office, is held the same week as the General Assembly at the United Nations, when most world leaders are in New York City.

WASHINGTON - OCTOBER 14: U.S. President Barack Obama speaks during a Town Hall on Viacom�s BET, CMT and MTV networks October 14, 2010 in Washington, DC. Obama appeared before approximately 250 young people representing a broad cross-section of backgrounds and answered questions from the studio audience as well as from viewers submitting questions via Twitter.

Supporters of Brazilian presidential candidate for the ruling Workers Party, Dilma Rousseff, receive a class on how to use Twitter and other Internet tools to spread information about the candidate in Porto Alegre, southern Brazil, on October 15, 2010. Rousseff and Jose Serra, of the Brazilian Social Democratic Party (PSDB), will face each other on October 31 in the run-off election.

MUNCIE, IN - SEPTEMBER 17: Twitter co-founder Biz Stone, talks about Twitter as he and David Letterman discussed the social media at Ball State University, Letterman's alma mater.

MUNCIE, IN - SEPTEMBER 17: Twitter co-founder Biz Stone talks about Twitter as he and David Letterman discussed the social media at Ball State University, Letterman's alma mater.

The Twitter homepage is seen on a computer screen in Washington on November 9, 2010.

The Twitter homepage appears on a screen in Washington on September 3, 2010.

MUNCIE, IN - SEPTEMBER 17: David Letterman (R) and Twitter co-founder Biz Stone discuss the social media at Ball State University, Letterman's alma mater.

MUNCIE, IN - SEPTEMBER 17: David Letterman (R) and Twitter co-founder Biz Stone discuss the social media at Ball State University, Letterman's alma mater.

MUNCIE, IN - SEPTEMBER 17: David Letterman as he and Twitter co-founder Biz Stone discuss the social media at Ball State University, Letterman's alma mater.

MUNCIE, IN - SEPTEMBER 17: David Letterman (R) and Twitter co-founder Biz Stone discuss the social media at Ball State University, Letterman's alma mater.

MUNCIE, IN - SEPTEMBER 17: David Letterman (R) and Twitter co-founder Biz Stone discuss the social media at Ball State University, Letterman's alma mater.

MUNCIE, IN - SEPTEMBER 17: David Letterman (R) and Twitter co-founder Biz Stone discuss the social media at Ball State University, Letterman's alma mater.

MUNCIE, IN - SEPTEMBER 17: David Letterman (R) and Twitter co-founder Biz Stone discuss the social media at Ball State University, Letterman's alma mater.

MUNCIE, IN - SEPTEMBER 17: David Letterman (R) and Twitter co-founder Biz Stone discuss the social media at Ball State University, Letterman's alma mater.

CHEPSTOW, WALES - OCTOBER 09: Rhys Flint rides William Hogarth (L) on the way to winning The Follow Nicholls On Twitter & Facebook Novices' Hurdle Race at Chepstow racecourse on October 09, 2010 in Chepstow, Wales.

HAYDOCK, ENGLAND - NOVEMBER 20: Shane Byrne riding Stagecoach Pearl on their way to winning The Follow Paul Nicholls On Facebook And Twitter Handicap Steeple Chase at Haydock Park racecourse on November 20, 2010 in Haydock, England.

CHEPSTOW, WALES - OCTOBER 09: Rhys Flint riding William Hogarth on their way to winning the Follow Nicholls On Twitter & Facebook Novices' Hurdle Race at Chepstow racecourse on October 09, 2010 in Chepstow, Wales.

HAYDOCK, ENGLAND - NOVEMBER 20: Shane Byrne riding Stagecoach Pearl jump the last to win The Follow Paul Nicholls On Facebook And Twitter Handicap Steeple Chase at Haydock Park racecourse on November 20, 2010 in Haydock, England.

NEW YORK - OCTOBER 28: Founder and creative director of Twitter Biz Stone attends the Huffington Post 2010 'Game Changers' event at Skylight Studio on October 28, 2010 in New York, City.

NEW YORK - OCTOBER 28: Founder and creative director of Twitter Biz Stone attends the Huffington Post 2010 'Game Changers' event at Skylight Studio on October 28, 2010 in New York, City.

NEW YORK, NY - DECEMBER 02: Co-founder of Twitter Jack Dorsey attends the 6th Annual Focus For Change: Benefit Dinner And Concert at Roseland Ballroom on December 2, 2010 in New York City.