I've got my Gainward GTX 480 and I'm very impressed so far. The upgrade from the 8800GTX is huge, massive performance gains in everything but that doesn't have to be explained.
Heat is not at an issue for me at all, the card idles between 45-47C (with a 120mm fan pointed at the heatpipes/grill) and the cards fan apparently is at 44% (GPUz) and it is very quiet, just as quiet as my 8800GTX that had an aftermarket heatsink (HR03+) and it idled at 47-48C with a 120mm fan (1200rpm)! The highest load temperature I have seen so far is 85C (60% fanspeed) and the card cooled down back to its idle temps in well under 5 minutes, and overall it has been more quiet than I actually expected it to be (under load and during cooldown). I almost wish it would kick up the fanspeed a little sooner and faster but I guess that has to be expected for the default autofan mode. Room temp are 22C.
So far I didn't try that many games yet, BC2 with 32AA and HBAO is so much more smoother than on the 8800GTX (no AA and HBAO), its crazy. I also tried out the Rocketsled and Raytracing demos, very cool stuff and definitely a little bit more demanding than BC2 but temp difference were only 4C (85C vs. 81C after playing BC2 for 25 minutes).
I'll report more later on, too tired to write/test more but I'm very happy with my purchase so far, impressive performance at a much lower price than I originally bought my 8800GTX for and there is no doubt what kind of a winner that little card was.