The site seems to have been hit by three simultaneous problems in the last 48 hours. Oddly, they seem to be unrelated.
First, the site kept crashing. Dreamhost tells me this is due to abuse by one of the other users of the machine I share, and that they are dealing with it. I hope the site will speed up as a result.
Second, comments stopped working. This seems to have been due to a combination of problems, one of which was that the MT-Blacklist plugin uploaded a regex from the updates site that gave it heartburn. I've deleted it twice, and if comes back I will have to stop the automatic updates. Comments are working now — if you encounter error messages (as opposed to sloooooowness), please contact me.
Third, I've had some erratic google API issues, which I think are resolved now.