So far, so good. Looks like minecraft has been put into a broken state because of some opengl nonsense, and jackd is now missing, but alsa-based sound is still working.
I always get a slight mental shiver when I see things like "bash" and "login" and "sudo" going by in the stream of packages being replaced and updated.
Huh, that uninstalled aptitude. Good thing I still have apt-get. Now time to go through and confirm the upgrade hasn't broken anything important. Vim and emacs still seem to work fine. Reinstalled jackd. Apparently it was just in some weird tangle of dependencies and package-renames. Supercollider still works with it. glxinfo still says it can't find a visual, so I'ma try restarting X11.
Aaaand of course X11 didn't start up the first time. Complained about not finding radeonhd drivers. Fortunately, a locate radeonhd found that I had left a copy of the source tree in my ~/build directory, so I did a ./configure; make; make install hoping it might fix things.
Because it installed into /usr/local/lib/xorg instead of /usr/lib/xorg.
After cping there, it magically came up. glxinfo gives me some good stuff, but minecraft still doesn't work --- albeit with a different error message.