Extrapolating from a recently filed patent at the U.S. patent office, it seems to have a transparent shell with a light source that will illuminate it from the inside.
Sensors inside will capture the light from the user's hand, and software will interpret the user's gestures and react accordingly.
I use all three (main) buttons on my Razer Diamondback on a daily basis. Still, it would be interesting if Apple is able to reinvent something so basic and prevalent.
How many buttons does your favorite mouse have, and how many do you actively utilize? Join the discussion.