Optical mice have been around for a while. I had one on my Sun workstation that came with a little metal plate you had to run the mouse over. It was a great mouse, except when I misplaced the metal plate and couldn't use the computer until I found it. But Microsoft's IntelliMouse line is even better because there's no metal plate. I can run it over my wooden desk, over my blue jeans, over the box the mouse came in, and it glides along happily, perfectly reflecting on screen what I'm doing with my hand. It's the mouse you've always wanted.
I was very fond of my cordless mouse for the six months that it worked. Not that it doesn't still report its movements to my computer; it does. But those movements have become so jerky and spasmodic that they no longer remotely convey my movements correctly. I've opened up the bottom, blown the lint off of the ball and scraped all the gunk off the little plastic rollers, but that just isn't enough anymore. But now I can give that rubber ball to my cat and toss the rest of the mouse away, because Microsoft has a ball-free, optical mouse that may make life worth living again.