Trackback spam has started to surface again, and like Matt, I see my “Goodbye trackback spam” post has been getting hit up quite a bit. I suppose “Moderating trackbacks and comments” is a good read, too.
At least for people running WordPress 1.2.2, I’m not sure what the best method of fighting comment-based spam is. I know podz has listed the methods you can try for yourself.
I’m currently using Kitten’s Spaminator 1.0RC7, but I’ve disabled trackbacks since that wasn’t working – at least until I upgrade to 1.5-beta. If disabling trackbacks will keep me from getting spammed, I’m fine with that.