It appears that I have experienced a catastrophic problem with my comments -- all of them are suddenly gone, not just from this blog, but from every blog on the installation. A quick search (all I have time for at the moment) reveals no widespread common experience, but maybe it's just difficult to narraow a search for comment problems. If you know anything about this, though, please shoot me an email.
(It's not the end of the world -- I should have a fairly recent backup.)
UPDATE: I have disabled the comments feature for the time being.