FrostyTech has some blurbage on new dual AMD Opteron self contained water cooling heatsink today. The system looks pretty advanced, and has been engineered by Hitachi of all companies. Here's a clip;

"The new self-contained thermal solution will be used with two AMD Opteron 2220 (2.8GHz) processors in the HP xw9400/CT Workstation. Low noise and heat management were primary reasons HP chose watercooling, and subsequently the system produces at most 26dB under high load."