I often forget I've switched away from it and it's still running! ATV should be smart enough to notice the TV is not looking at it anymore and switches off automatically after a time out. HDMI is an intelligent interface right? My Sammy BluRay player does this, it switches my Sammy TV automatically when it needs attention and it sleeps by itself if it detects TV is not looking at it. Me thinks the kids at Cupertino is spending all their time on iPhone/iPad.