My iMac (3.06 i3, 21") is used as a media server for my Squeezeboxes and Apple TVs. Since it's on 24/7, I turn the display off when not in use to save power, display life, etc. Since upgrading to Lion yesterday, I cannot keep the display turned off. If I use my hot corner, it comes back on almost instantly. Haven't had a chance to try it when it isn't "serving" something - are the USB and Firewire externals keeping the display awake? Any way that I can turn that off?