I'm finding that cleaning the ball WILL be an eventual necessity! Today I had my first "sticking" ball, with something stuck under it. Blowing and moving it got it out, but I'm telling you. One day it'll be like that old ball mice at the computer lab!
Anyways, but this is a problem. I really dont see why Apple didnt go with individual touch sensors for the left/right click, and now it seems like a pressure sensitive "dome" would be a better idea than the traditional ball.