This month's Next Generation magazine has a piece on the internals of the Sega Dreamcast game system available now in Japan and soon in the USA. It uses a liquid cooling system with distilled water that transfers heat from the SH4 CPU and the Hitachi graphics chip over to the outside world. It uses a thermistor to shut down the system if things get out of hand. I haven't found any details about whether the system uses convection or an actual pump to move the water.
Slashdot Mirror
Kriston J. Rehberg
http://kriston.net/