Facebook's busted, taking the web down with it
Looks like Facebook Connect has gone a crapper, and sadly it seems to be taking a lot of the internet down with it. If you're having trouble getting to where you want to go, logging out of Facebook seems to sort things out again. Not much else is known at this point, other than maybe being dependent on single-point-of-failure networks isn't a great idea. Hopefully they fix this up quickly.
Meanwhile, let us know if you're having trouble, and when/if things start working again.