Running the latest Lion, I can sleep my display via a hot corner, only to have it randomly wake up with no user intervention. Its just the display, the Mac isn't set to sleep at all. The time interval isn't consistent either, it can be 5 minutes or several hours, but needless to say, its highly annoying when I myself am trying to sleep and the screen randomly cuts on for 5 minutes, goes to sleep, then wakes back up after a random amount of time, basking me in light.