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Facebook Holds Its Fourth f8 Developer Conference

SAN FRANCISCO, CA - SEPTEMBER 22: Facebook CEO Mark Zuckerberg delivers a keynote address during the Facebook f8 conference on September 22, 2011 in San Francisco, California. Facebook CEO Mark Zuckerberg kicked off the conference introducing a Timeline feature to the popular social network. (Photo by Justin Sullivan/Getty Images)

Facebook's f8 conference

Facebook unveils a range of new features at its fourth annual f8 Developer Conference in San Francisco.