Well, that was relatively painless, I guess I'll see what breaks in the immediate future, especially once I start screwing up\^W\^Wediting the templates.

For the record, all I did was to create a new database to hold the new version's stuff (I use postgres, so createdb mt4), then I exported all the old stuff using MT 3.2's import/export interface, moved the old stuff out of the way (the static /blawg and the dynamic /mt), dropped the new MT4 into place, configured it, imported the old entries, and there we go.  Importing the old stuff took a while, and then publishing it took forever.  I'm glad I'm not that prolific.

Now I just need to figure out the new stuff, like tags and keywords...  I've enabled trackbacks again, to see how things go with that, I disabled them before because they caused way too much spam.