CPU:s are getting cooler now, OK, we´ll see what the quad cores will give us, but I think the graphic cards are the next objekt for watercooling. Just take a look at the immense heat sinks on a new high end graphic card, and still the noise levels can be bothersome, to say the least, when You´re pushing them through latest-and-greatest games.
The replacement GPU-cooler market is increasing everyday, etc. Plus ventilation fans to get the heat from the cards out of the computer case.
I think water cooling still has a place, not on the CPU:s but on high end graphic cards.
regards
Mikael S.
edit: Back in a few mins with power consumptin values to back up my thesis.
back again:
http://www.vr-zone.com/?i=3335&s=8
a few graphic cards and their power consumtoins. You can overclock an Intel 2 Core quite a lot before it eats more power than 2 Crossfired X1950 XTX