There was a period of about 24 hours when comments were disabled on my blog. What happened is that somebody figured out a way to send out spam that appeared to be from my blog. To get to the root of the problem the comments had to be disabled for a while.
The problem is solved now, and the comments are working again (in fact, they have been for the last 24 hours). But in case anybody tried to comment while they were down, and got a nasty looking “Forbidden. You do not have access to this page” message, I apologize and you can try sending your comment again.