I was told recently of a pretty disturbing new trend - Facebook Spam (or FaceSpam). One version is that bots can go through the Facebook database and request to be friends with somebody, using the optional message feature, where the spammer would put their shpiel. This is one loophole for people to send messages to someone they're not friends with (and really, who would befriend a spammer).
A much worse one (IMHO) is that a spammer could "poke" a user. If the user is dumb enough to poke the spammer back (as I was), the spammer will be able to see the user's information for a week (one of the side effects of Facebook's "poke" feature) - ample time for the spammer to grab all of the victim's information (to be honest, I'm not sure I was poked by a spammer - it may have just been a friendly stranger). Definitely something for you Facebook users to look out for, though.
p.s. Yes! One more thing to worry about! I'm going to have to blog something positive and fast!