The Axiotron Mac OS X-based "ModBook" tablet computer apparently was an hot item and a crowd pleaser at the Macworld 2007.
Axiotron modifies Apple MacBooks and turns them into Apple Tablet computers.
Wacom Penabled hardware is apparently used for pen input
Axiotron uses Inkwell handwriting recognition software for text input.A Modbook is starting at $2,199 and will be available through OWC. You can pre-order the modbook now.
Apple Insider has more details and several cool hi-res photos of the Modbook displayed at the Macworld 2007.