Hardwarecanucks posted a review on the Thermalright HR-11 Backside Cooler.
A quote from the article:
Thermalright HR-11 Backside Cooler Review
Thermalright has once again surprised us with an innovative and imaginative design which works better than we would have thought. A backside cooler definitely seems to be a novel idea considering the waves of heat we have felt coming off the underside of an 8800-series graphics card. Even with the rising temperatures, the HR-11 has shown quite well that its positioning can tame the rampant heat of the G80 by lowering temperatures of the GPU core.
Thermalright HR-11 Backside Cooler Review