Surprising, because I'd totally forgotten about it and really wanted to see what this was all about (after reading some of the comments here).
So I thought to myself 'ok, this once' knowing I'd be sticking my head out. It took me a minute or two to realize the cause and I thought that was a nice side-effect of solving this at the DNS layer, even when you're momentarily stupid this will still create enough of a barrier that you'll stop to think a bit longer.
I didn't know about the ghostery extension, so thanks to the person that posted that, that's another good solution.
FB has had its use for me (it found a bunch of long lost people), I haven't been back since.
i'm guessing that you actually have a bunch of other sites blocked in your hosts file, as well. on the assumption that you do, do you ever see any network performance issues related to this? i used to maintain a rather large hosts file for this purpose, but eventually gave it up because i suspected that it had started doing more harm than good.