A man checks facebook on his smartphone

A man checks facebook on his smartphone while waiting for a train in a metro station in Washington, DC, on May 9, 2012. Mere weeks from a multi-billion-dollar debut on the stock market, Facebook has ramped up its focus on mobile lifestyles with the purchase of "social discovery" startup Glancee. Facebook has made a priority of following its users onto smartphones at the heart of Digital Age lifestyles even though the social network has yet to make clear how it plans to make money doing so. AFP PHOTO/Jewel Samad (Photo credit should read JEWEL SAMAD/AFP/GettyImages)