I was wondering if something like the Power Nap that is supposed to be limited to the MacBook Air and Retina MB Pro is running on our Mountain Lion desktops? The reason I ask is that since updating to ML, I have noted two occasions where my Sleeping MP 5,1 has half woken up for about 10s (fans, USB Power but NOT monitor), done whatever it wanted to and then gone back to Sleep. Pressing a key while it is in this half-awake state does not wake it up fully. I have to wait till it is done and then wake the MP up. I also noted that immediately on waking, the New Mail notification (top right) was present even though my internet connection would have taken a couple of seconds to poll for mail after waking.