Got tired of all the comment spam, so I finally bit and did an upgrade to MT 3.2. Upgrade process was fairly painless, except that most of the comments showed up as pending, but didn't show up easily in the admin interface. It seems like I'm getting more comment spam than ever, but at least they're all getting trapped, and I can delete them at my leisure without them getting published.

Maybe some hot WordPress action is in my not-too-distant future...