Yup... my B3 Q6600 is a toasty little sucker and I only run mine at around 3.15GHz. Water, for now, is the most efficient cooling method you can use. I am looking forward to seeing the micro-channel cooling tech develop some more to see what it can do.
Just make sure you do your homework. A good watercooling setup will last you a good long while as long as you properly take care of it. It will last numerous generations of hardware upgrades. Just make sure you pick a waterblock manufacturer that will always have new mounting plates in stock so you can stay with the socket format changes.
*cough* DANGER-DEN *cough*
