Apparently FB is just popular enough to get the occasional bit of robospam in the comments. I've deleted all the ones that have gotten through, but since this kind of thing only gets worse, I've had Mikey drop a Recaptcha module in. This only affects you if you're not logged in. The alternative was shutting off comments from users who weren't logged in, and I know a lot of you use that. Plus, Recaptcha serves the public good.