I think this would be really cool. It seems most tablet pc's have been aimed at business people and students, good for jotting down notes and giving presentations. I see thet apple tablet as a very good tool for graphic designers and artists. Macs are very popular with artists and combining the Mac OS with the ease of drawing using a stylus would be a good thing for them. (This is all assuming that they give it enough power to be useful) This is a small niche, but its also just a non-windows option for people that want a tablet.

Just my thoughts.