I have one of the new iMacs too with buildin iSight and it's weird, sometimes when I take pictures with PhotoBooth my face is all pale(it is rather pale though) and sometimes my face is colored like the way I would see it in the mirror in the bathroom. I have the same amount of light when taking two different pictures but different outcomes. If I put my hand up infront of the iSight I get nice colors but as soon as I remove the hand I get all pale and stuff.
But mindwaves, you'll be glad to know that iGlasses is now updated to work with the new iMacs.