Yes, we are aware of it. I possibly should have said something in the big post (though it was getting a bit weighty already!).
Lets call this comment my first techpost :)
Basically, the image storage may be slightly un-optimised, and we were running low on space.
When the upgrade happened, the space available became completely full, and the upgrade kept failing.
Tom tarred up some of the images, and put them in a storage location to give the install breathing room.
Because Emperor and I are planning to migrate anyway, the aim is to restore this once the migration is complete (no sense complicating things).
For a more technical answer, the image serving system splits the image files up into multiple folders.
I believe the smallest top-level one was removed (least impact).
Once the site is migrated, we're going to have a much larger space, and fingers crossed, I'll get things restored.
And yes, it's really bloody annoying to me too. I've lost my avatar!