Actually, it is a tablet, people don't know. The lcd display has microchips under each pixel that detect touch. It requires a little bit of modification, but it should work. You just need to spend hundreds of dollars, tons of time writing a program, and other stuff.
Actually, I'm joking.
Not really a tablet, does the iMac g5 have a battery? Even then, how would you use it. :s
Err, no.. since it requires a USB keyboard, USB mouse, no touch screen, it's heavy, etc. The only similarity is that it's flat. Maybe if I taped 10 PDAs together...
Although that certainly looks fascinating, I hope neither Mac or Windows is smart enough to do something like that. It just seems over the top and useless.