Interesting issue I've just discovered in Snow Leopard. For some reason my Mac Pro is waking from sleep on its own. Furthermore, it won't go to sleep on its own after the set duration (3 hours). When I manually put it to sleep it wakes up again at some point. I come into the living room and bam, it's on. Weird..... I haven't noticed any unusual processes running that would cause this. And when I put it to sleep I have no apps running. Anyone else notice this?? My Mac Pro could sleep on a dime prior to SL.