I guess that's what you get for having a UPS on the floor under your desk, with the "test" button right about toe height. Unfortunately, the UPS in question has a battery more than a decade old, and my little test amounted to little more than pulling the mains plug straight out of the box.
Ubuntu 7.10 booted right back up, and I logged in again with no unusual messages or warnings. I pulled up firefox and restored it's crashed session, and here I am. Apart from an article I hadn't saved in Joomla, I didnt lose anything.
Note to self, I need a new UPS for the office. I should probably get one for the media centre box in the lounge room too.