The constant battle of comment spam
Since upgrading this blog to Movable Type 3, I've been fighting the comment spammers on a daily basis - usually having to delete somewhere around fifty bogus comments with embedded links to various porn or cheap drug sites each morning. I've really been missing Jay Allen's wonderful MT-Blacklist plug-in, which allows you to block spammers as they attack your blog with bogus comments.
So I'm pleased to see that MT 3.1 will feature a pack of plug-ins including the return of MT-Blacklist. 3.1 is due to be released at the end of August. Huzzah!
[update] Call me slow, but I just discovered the Concerning Spam page from Elise Bauer's wonderful Learning Movable Type site. She recommends renaming the MT comments script, which Jim Flanagan told me to do months ago - so now I've done that and we'll hope for the best!

FWIW, since I switched to WordPress, comment spam has ceased to be a problem.
There is now an MT 3 compatible version.
See http://www.jayallen.org/comment_spam/2004/08/mtblacklist_v20e_released