Regnerating archives with rewritten history
I just fixed a subtle but really stupid bug in the regeneration code which would cause it to not update some weekly archives if one had sufficiently rewritten history (i.e. changed the display dates significantly on enough posts). It's really amazing how much work it can take to figure out which are the three lines that need changing.
Anyhow, thanks to Steve's help in figuring this bug out, it's now history.