Crossover - Works, but it is slower to start AMVapp programs, and you might need to try to start a given program more than once before it appears. Annoying, but I will keep you updated on whether later versions or experimental builds solve this problem.
Avidemux - If you have a MacOS build prior to 2.4.4, please update. Snow Leopard will break earlier versions. In addition, Surfer has started work on a MacOS build of 2.5.0, but it only runs on Leopard at the moment.
Quicktime X - No longer seems to recognise mkv files, but Perian is running correctly, far as I know. Using other programs that access Quicktime components seem to be able to open mkvs just fine.
So far, Final Cut, Premiere CS3, and Photoshop CS3 seem to work fine.
I now designate this the official, "Goddammit, Snow Leopard broke my [Enter Program Here]" thread. Please put all queries of that nature in this thread.