Which would mean there's nothing wrong with the app. I think what's going on is the Installer has screwed up permissions. I didn't have an immediate panic. It just wouldn't restart. Something was holding on tight and not letting diskmounter let go. Eventually, I got the Installer disk to boot it (Mac G5 Dual 2.0), and I clicked on "Repair disk." It stopped immediately, and said it couldn't unmount my regular drive. So I ran permissions, and it worked. There were 3 or 4 things there -- 0's that should be 80's, that sort of thing. Nothing major.

Then, I ran disk repair, and in two minutes, everything was fine, and I'm now booted up.

That's my initial guess, anyway: a good update, with a crummy installer that was tacked on without many tests as it went out the door.