Putting aside one's opinion on Facebook's stance around privacy, I think Facebook is one of the sites with the best measures to insure integrity of the site, at least for a consumer site.

A few times, I was warned that someone tried to accessed my account from a different computer, and went through a multi-step process to prove that I was indeed me. And, though it was multiple steps, it wasn't too much of a hassle actually.

Another time, one of my friends' account was compromised by a scammer and I got the account shut down in a couple of hours.

Recent activity and global logout is pretty useful. I imagine Facebook will offer a two-factor authentication at some point down the road.