New Form of Comment Spam: TrackBack Spam

I was just hit with dozens of Movable Type TrackBack spams: that is, links that will show up in my TrackBack link for a given article. I hadn't even thought about this kind of spam. These spams are hideous: anal rape, etc., etc. Lovely. Okay, how do we fight TrackBack spam? Fortunately, I must have misconfigured Movable Type: it's not showing any TrackBacks.I looked into how to fix this problem and found no good answers. I wound up just disabling the TrackBack script so that people can't send TrackBacks. I'm not sure how this could be salvaged.