I just started mining with a new (and dedicated) box using the card in the topic, running LinuxCoin 0.2a. First, using AMDOverdriveCtrl just to keep an eye on the fan settings and temperature I'm seeing that temp once everything is going, using the normal automatic fan control choices keeps the card right around 79.0C. This seems very high. If I take over setting the fan speed and run it up to 90% I can get it down to 77C. I've tried clocking down the memory controller but if I go below 680MHz the software "auto-corrects" or something and pushes it all the way back up to max, and this didn't have any impact on the temperature.
Finally, I'm "only" getting 315Mhash/sec (either poclbm.py or phoenix with either kernel), which isn't the worst score from the Mining hardware comparison page but isn't quite what I expected either. I've played around a little with forcing LinuxCoin to use the 2.1 SDK instead of 2.4 and didn't see any change (and yes I re-compiled python-pyopencl against the new SDK).
Thanks for any hints!