I've installed the new upgrade to MT-Blacklist to blogfodder. Hopefully this newer version will further reduce the number of such incidents we all have to deal with. Blogfodderians who do get any can email me and I'll send the URL for adding IP addresses to the banned list.
One of the new features is the ability to search existing comments and "de-spam" them. I just ran the search on the 1,000 most recent comments on all blogfodder blogs and was able to eliminate 50. After midnight, when traffic is lower on Jade, I'll run it for a really large number and see is we can't eliminate the problem altogether.