Ever since little Kosovo proclaimed itself an independent state five years ago, it has failed to win all the recognition it so craves. Neither the United Nations, which confers legitimacy, nor all the European Union, whose members are divided on the question, much less Serbia, from which Kosovo broke away, recognize the birth of a new European nation. But after a campaign waged by an army of devoted Kosovars and strategically placed allies, Kosovo is hailing a grant of legitimacy by a new arbiter of national identity: Facebook.