Why? Everything available to Facebook, I voluntarily put there. Just as anything I say in a comment in their widget will be voluntarily contributed. As a Facebook consumer, a single identity across all my comments tied to a service I already enjoy makes Facebook that much more useful to me. Let them do with the data I gave them as they please.

Hell, I am far more concerned with how much credit agencies seem to know about me, and I never like giving my information to them =p.