Yea, I would also like to know where you got this, how much it cost, and how your temps are with it.
The only thing I worry about now, is that I will need to somehow cut the bracket on my card since it is an ultra, unless I can somehow find a bracket with space for 2 dvi outputs, and switch it out.
I got this and many others from someone I know at http://www.scythe-usa.com. They will be available Aug 20 (tomorrow). Unfortunately I don't have a true thermal diode to read temps. The onboard sensor shows approximately a 5C drop at idle and load, which isn't much. But it did help me overclock the core 25MHz greater and it is actively cooling the memory. I think the best feature is that it dumps hot air outside of the case rather than circulating it inside the case like the stock cooler does.
The Reaper that is pretty expensive. The most expensive one on Scythe is $30. I'm using the NV Silencer 5 and ATI Silencer 4, but I am selling an ATI Silencer 1 and 3 that I have no use for, for $25 shipped.
PCUnleash has a review here that tested the 6800GT with the Ultra stock heatsink/fan against the NV5 Silencer. The 6800 GT actually ran hotter with the NV5. Why they tested the GT with the Ultra cooler I have no idea. The only thing a Ultra owner might gain with the NV5 looks like a quieter video card, albeit at a hotter temps.