It never goes above 54c. If my roommate isn't home, I've got the heat cranked down to about 64F and the card stays between 50-52c. And its win-win for me since I like being a little more cold anyways.
This is in a HAF 912 with 4 120mm fans (two front intake, one intake on the side blowing air just under the video card fan's intakes, and one exhaust out the top back) and a 200mm exhaust out the top. My CPU cooler is a Cooler Master Gemini II.
I'm gonna go for 1GHz core later today so we'll see how it goes. I plan on finding how low I can go on the voltage at 900MHz core after for a more stable/long term OC.