I might be the last person to hear/talk about this, but I've found that the spam blocking plugin built into Movable Type 3.2 has been sucking lately. This morning I got about 100 blackjack spams, which confused me because I figured after I marked the first 50 as Junk, the system would be smart enough to know. Guess the new system isn't that smart. Anyway, I recently found the Wordpress Akismet spam blocker is available for MT. Seems to work very well. You need a wordpress account to get an API key, other than that though, there's nothing you see in the interface other than a huge lack of spam comments/trackbacks.