I moved the blawg between physical hosts and also changed the base URL from /blawg/ to just /, since that's how all the Cool Kids do it and I wasn't updating anything at all besides the blawg anyway.
I figured while I was breaking things, I might as well go all the way and switch to the RC4 for MovableType 4.2. I made an unpleasant discovery that while 4.1 will backup and restore, 4.2 will only backup. So I had to export my posts from the old installation (fine, wanted to do that anyway) then import them into 4.2, but as a result I lost some settings - my pretty green! - and also some spam comments got accidentally published.
So far, I'm actually not impressed with MT 4.2 - despite its vaunted speed, and the faster CPUs in the new host, it still took 27 minutes to do a full publish run. Then again, it was starting from complete scratch, so maybe next publishes will be faster.
Hopefully this won't break MarsEdit! (It didn't.)
Changed the base dir back. Damn second thoughts. Plus it broke RSS feeds. I'm too lazy to figure out the rewrite-fu required, plus I was worried about MT stomping on stuff in the base dir. Maybe some day I'll do the reverse: redirect / to /blawg. And I have my green back, but not the BANPC blogroll at the side - I'll fix that later.