Pretty much looks like 24 dual opertons in a big box with 6 u320 drives each and a gigabit network card. You could setup something comparable under *nix at your house.
in fact, after reading a bit more im almost positive thats what it is. they just twist the terms on the specifications page to make it sound better than it really is..
The Cray XT3 processor and I/O boards use socketed components wherever possible. The SeaStar chip, the RAS processor module, the DIMMs, the voltage regulator modules (VRMs), and the Opteron processors are all field replaceable and upgradable. The Cray XT3 system backplane is designed to allow modules to be hot-swapped to replace faulty components without the need for a system shutdown, enhancing system availability. All components have redundant power, including redundant VRMs on all system blades.
So, they use normal memory, have a DPS module (as gigabyte calls it), Opteron processors, Yes thats right! you can take off the heatsink and swap your opteron processor, wow.. thats like... unheardof.... Hotswap has been around for a long *** time, redundant power (so they have a failover system such as most servers have, 150$ on pricewatch), Redundant voltage regulators, wow... i always wanted one of those! You can buy a powerfilter for 100-200$. I have one, they're awesome for audio recording. If you wanted a setup like that, you're looking at like 1500$ish per blade, as opposed to the cray price of like 500,000$ or whatever their mainframes start out at.