Facebook CEO Mark Zuckerberg should be relieved to learn that someone is at last "leveraging the social graph," as he might put it, for financial gain. Problem is, it's not Facebook. It's hackers pulling a phishing scam. A tipster tells us his friends at Facebook are busy fighting a virus that tricks a user into opening "a YouTube phishing site," delivered in the form of a Facebook message from one of the user's Facebook friends.