They're back again, 100+ blog spams for some casino. Rather then delete them automatically, I added the mt-blacklist plugin. It includes the ability to bulk-delete comments based on IP address.
Interestingly enough, last week's anti-blog-spam measures didn't really help--the spammer followed the comment form right to the new, renamed comment CGI. So, it looks like we're headed for a real spam arms race. Bastards.