It looks like in the upgrade to WordPress 2.5, I inadvertently lost all the uploaded images up to that time. I back up the database nightly, but ancillary stuff? Apparently not.
To be clear, I did have a backup of the whole mess from the upgrade: I moved the old wordpress directory aside, set up the database connections, repopulated/upgraded plugins and themes. But never moved the uploaded images back. And I remember deleting that huge file, thinking I didn’t need it, just couple of days ago. Almost 6 years of it all, too.
Ouch.