Updated to the latest XBMC beta. It messed up most of my show icons and watched/unwatched status, and for some reason defaulted my sound output to a virtual device instead of the output I'd had it set to previously, but I've got it mostly-fixed now.
There really is a lot to love about XBMC -- it's certainly the best software I've found for easily indexing a video library -- but man it sure is fiddly.
But hopefully this version will fix the previous "stable" version's habit of locking up my system and my video output and forcing me to log out and back in to fix it.