Apropos of nothing in particular, I've turned off anonymous comments. Commenters must now register either with Blogger (highly recommended, since it gives you the option to receive email notification of comment replies) or another OpenID provider such as Wordpress, Livejournal, AIM, etc.
If you find this hugely inconvenient, send me an email and I'll reconsider. (I strongly dislike seeing 'Anonymous' appear in the comments, though. He's an unpredictable and not entirely trustworthy fellow!)