Facebook CEO Mark Zuckerberg speaks at Facebook headquarters in Menlo Park, Calif., Thursday, March 7, 2013. Zuckerberg unveiled a new look for the social network's News Feed on Thursday, the place where its 1 billion users congregate to see what's happening with their friends, family and favorite businesses. (AP Photo/Jeff Chiu)
Facebook CEO Mark Zuckerberg gestures while speaking to the audience during a media event at Facebook headquarters in Menlo Park, California on March 7, 2013. REUTERS/Robert Galbraith
Facebook CEO Mark Zuckerberg gestures to members of the News Feed design team during a media event at Facebook headquarters in Menlo Park, California March 7, 2013. REUTERS/Robert Galbraith
Facebook CEO Mark Zuckerberg speaks at Facebook headquarters in Menlo Park, Calif., Thursday, March 7, 2013. Zuckerberg on Thursday unveiled a new look for the social network's News Feed, the place where its 1 billion users congregate to see what's happening with their friends, family and favorite businesses. (AP Photo/Jeff Chiu)
Facebook CEO Mark Zuckerberg gestures while addressing the audience during a media event at Facebook headquarters in Menlo Park, California on March 7, 2013. REUTERS/Robert Galbraith
Facebook CEO Mark Zuckerberg speaks during a media event at Facebook headquarters in Menlo Park, California March 7, 2013. REUTERS/Robert Galbraith
Facebook CEO Mark Zuckerberg addresses the audience during a media event at Facebook headquarters in Menlo Park, California March 7, 2013. REUTERS/Robert Galbraith