I'd be interested to see what the temps were like on the Air when it's driving everything through the Thunderbolt port. I guess we'll see when the TB displays start shipping.
Additional Thought: I'm wondering if the TB display would take video from my PC. I've got a 5870 in my PC rig, that has a Displayport out on the card. Of course I'd have to get a DP>mDP adapter for it--but it would make the decision on purchasing it a lot easier for me ^_^