Hello,
I've just upgraded my wiki installation at http://www.sca.org.au/cunnan/ to 1.2.1 and noticed a two things: * $wgUseCategoryMagic =true; causes all article space links to disappear. (unsurprising?) * upgrade.php didn't update the recentchanges table. I had to add rc_type, rc_moved_to_ns and rc_moved_to_title manually.
Otherwise everything went as expected, I'm not sure the second problem was something I caused or a mistake in upgrade.php
Tobin.