I had some trouble with Gatekeeper earlier, but I think it was primarily due to the fact that I have multiple themes on my blog. (I also saw a note in the Gatekeeper changelog about a bug that blocked trackbacks and/or pingbacks in the version I was using.) I’ve upgraded Gatekeeper to RC4, and I’m going to disable the theme switcher (and my other themes). Then I’ve got to hard-code a call to Gatekeeper’s challenge routine in my comment form(s).
Sounds like a job for this weekend, since it’ll probably take a few hours to get all this done. God, I hope that You have a special circle of Hell set aside for spammers!