Interesting new hardware from SGI. It seems like a desktop-size "blade server" that supports up to 80 cores, and runs Linux or Windows. Price starts at $8K, and "a fully populated enclosure with 10 dual-socket Intel Xeon L5520 processor nodes, 240GB of memory, and integrated GigE has a list price of $53,000." Not the most cost-effective farm, but possibly the most space-efficient.
News story:
http://www.hpcwire.com/features/SGI-Makes-Leap-Into-Personal-Supercomputing-60079687.html
Press release:
http://www.sgi.com/company_info/newsroom/press_releases/2009/september/octaneIII.html