Thanks. After reading that, I downloaded a copy of my files and used diff to compare them with the latest WP. Found a few extra files, but nothing looked too suspicious. Still, they’re gone now. Of course, that doesn’t include wp-content.
I think the biggest potential danger there is the cache directory, which I note is not in the current WP. I thought it was active, but I just noticed its modification time was 6/09, so I’ve deleted it. Hopefully the culprit was hiding somewhere in there. If not, I guess I’ll delete and re-add all my plugins. Hope this helps someone.