Oh, so you mean the little round mice that came with the iMac Blueberries? ;) (Those were awesome, in their own right, in my opinion, simply because they were so different from typical mice.)

But yeah, the new Magic Mouse is really cool. The basic software that currently comes with a Mac only enables it to do basic things, such as right click and one- and two-finger swiping (one for scrolling, in all directions; two for forward and back navigation). The right click is a little awkward because it doesn't always pick up that you're clicking with the right finger (it's based off touching with both, then lifting the left up and clicking with the other), but the scrolling, especially is really cool, particularly when image editing. Then, there's third-party software that allows it to do all sorts of stuff. A coworker of mine had the software and he had it opening files with particular touches and such. It's like having a second keyboard solely for shortcuts, for those that are into that.

It's also blue-tooth and has pretty damn good battery life (that batteries that came with it lasted two and a half months).