Is there a $50 billion business plan?

Everyone has heard the thrilling Facebook story. Goldman Sachs has injected money into the social network which raises its value, on paper at least, to some $50 billion. Much further down in the story is a chilly draft of air however. Facebook may be able to generate $2 billion in revenue this year. Established companies whch are now valued, on paper, at less than Facebook, will earn ten times that much. Of course Facebook has stunning access to its audience. Nonethless, it would be nice to hear about the business plan.