Apple has already released their developer Kit for OSX on the Intel platform and an enterprising Tablet PC Buzz member Charles Alexander has installed it on a Toshiba M200 Tablet PC. Follow his journey here. His initial observations:
Screen rotation, the network card, wireless, the modem, USB, the touchpad, and I’m sure plenty of other stuff isn’t working. But with apple’s inkwell ( http://www.apple.com/macosx/features/inkwell/ ) this thing is really showing potential. After messing around with this thing for a few days I can’t believe apple themselves never released a tablet.