I guess facebook has truly become a utility: It's a semi-monopolist users hate, but they find it too hard to cut the cord. Sounds like AT&T, Comcast etc.
I remember how quickly people stopped using IM and moved their entire online presence to Facebook, including the announcement and discussion of planned events.
As an IM user who never moved, it kinda sucked. :)
I guess you could say the same about the move from ICQ to Windows/MSN Messenger, though.