Yes, the iSight comes with several mounting clips for the iSight to be mounted in PowerBooks, iBooks, and Apple displays. Not sure if there's a clip that fits the older non-aluminum Apple displays. Apple also sells extra clips in a kit so you can mount the iSight on several displays and not have to take the clips off.
As for fitting on non-Apple displays, I have no idea. The slips are adjustable so you might have some luck. It shouldn't be too hard to fasten a clip or make one for a non-Apple display.
I heard the rumor of new iSights. What would Apple improve? A smaller camera? Faster framerate, better color, USB support? CHEAPER would be nice too.