Over the weekend my WordPress version was updated under me from 3.5.1 to 3.8 (actually the entire system was upgraded). The person who did it did not realize that I had my own code changes to reduce spam comment postings, and these changes vanished, as did customizations to the php.ini file which ultimately controls stuff like how WordPress sends e-mail.
Because of the former update things changed from two or three spams per week to 5 to 10 per hour. Because of the latter change I was not getting any e-mail telling me these comments needed moderation.
The e-mail is fixed now and I should have the anti-spam code in very soon so things should be back to normal shortly. Visitors to the blog will not have seen any functional difference.
As fate would have it, all the spam from the last two days actually included one legitimate comment, which I almost threw out with the rest of the trash!