"The one and only tablet Mac", but not by Apple. Axiotron has taken a 13 inch MacBook and turned it into a GPS touting, pen based input tablet PC.
It runs Leopard, has the built in camera and is compatible with Apple's inkwell which gives system level handwriting and getsture recognition. All this comes at a price though. Listed at $2290, it can be ordered through OWC or Carbon Computing if you are north of the border.