So it seems that around the time I went to go sit down with my son to try to get him to take his nap (didn't work, by the way), there was a bit of a kerfuffle over triciawyse getting banned for no apparent reason. I didn't have my mail program open on the laptop, so I didn't hear about any of this until Markos called me (which is a Big Fucking Deal™, believe me).
Anyway, what happened: she managed to post so many comments in a short period of time, she triggered the posting timeout. When this happens, if you keep trying to post comments it'll double the timeout, until such time that you exceed the maximum timeout and you get autobanned.
Nothing nefarious, here, and it's very hard for a human to trigger the timeout. It only looks at the number of comments in a very short time, not how many you've posted overall. Those of you who have managed to post 40,000+ comments are safe (unless you tried to post them all in five minutes).
I am, however, checking to make sure that you actually get notified of the timeout. It's so hard to do that it's never really come up, and subsequent changes to how things work may have blocked the commenter from actually getting the notification. There was also a bit of a delay in getting the problem cleared up because I was accidentally working on fixing it on the database server, which wasn't the right place. Ooops.