What you need is three identical 3D Vision-compatible displays (such as Alienware's 23" OptX AW2310), two Nvidia GTX 260s or better running in SLI, Nvidia 3D Vision glasses, Windows 7 (Vista and lower aren't supported) and, of course, the latest GeForce beta drivers. Of note, the GeForce GTX 295 in Quad SLI won't work at the moment, but that should be resolved soon.
All of that will amount to somewhere above the $1,500 mark, considering the fact that mentioned Alienware screen is $450 alone. The payoff? An unfair advantage in real-time strategy games, according to the above video which was posted on the Nvidia Ntersect blog. Another video shows a Maingear Shift PC with a custom cooling system and two GTX 480s strapped to the rear of a hydraulic-powered racing simulator.
Windows Vista and 7 (x86 and x64) users can grab the 258.69 beta driver in our download section, which also has information on new features besides 3D Vision Surround support.