From personal experience, if there is absolutely ZERO air movement it will get a little warm to the touch, but temps were always pretty good, as soon as there was a slight bit of air movement, I say slight as I had a really cheezy low cfm case fan handy I got it to room temp within 30 seconds. Basically if you have the airflow that pretty much any descent (not great, just descent) case has, the chipset block stays pretty cool. MUCH cooler than my X58 FTW3 did (before it went on water).
At some level it would be cool to have it on water too, but after my own usage of it, outside of "coolness factor" I don't see a need. If Nate does opt to though, maybe he should make some kind of sig for it, like a "Cooled by NM_D" engraved onto the block :D