Got rid of the stock cooling right away, running an Accelero S1 with a 120mm S-Flex. I'm idling @ 33C and loads are peaking at 41C, although that was @ 700MHz, I'll report back what 750MHz does...
Unfortunately it doesn't look like this tool works yet with 2D and 3D clocks, as it's set to a constant 750/1100 instead of clocking down to 500/750. There are options listed to set both 2D and 3D but it won't let me access them to set them individually...
I'm thinking nVidia is in for a rough ride once we start seeing some 4850 OC editions that come packaged with decent coolers - with the S1 installed I could easily bump the core right up to the 700MHz max that CCC allows.