This "supercomputer" is purely a marketing gimmick by the Air Force, to make them attract people from the gamer audience. The Air Force, as I'd learned, is desperate to reach out to that sort of demographic, and they feel that by boasting they have a lot of PS3s, they can make themselves seem better to these potential recruits.
Well, here's the lowdown: the the PS3 makes a terrible supercomputer node. Why's that? It's because its Cell processor was not designed for double-precision. The PS3's CPU gets an admirable 211.2 Gigaflops of performance in single-precision math... But single-precision is only good for media and gaming tasks. Actual scientific, engineering, and HPC tasks NEED double-precision. And at that... The Cell trails badly, dropping to about 32 gigaflops.
Computers are an engineering thing: you CAN'T have a design that's best at everything. You have to sacrifice one thing to get another. The PS3 sacrifices any real supercomputing capability in order to be good at being both a gaming machine, and a high-definition media center/Blu-ray player. The flip side is that for this "PS3 cluster," the Air Force is only getting a measly 56.32 Teraflops of actual supercomputer power. (the RSX is a GeForce design that pre-dates CUDA)
If they wanted a real supercomputer, they'd use IBM's modified supercomputer variant of the Cell, the PowerXCell 8i. This is what's ACTUALLY used for supercomputers: it natively handles double-precision, and gets 108.8 gigaflops instead of only 32. That would bump the machine up to nearly 200 teraflops of power, which would put it in REAL major supercomputer territory. That, and IBM MAKES PowerXCell blades that are made for this, and are VASTLY more energy-efficient than using PS3s.
It's kinda telling: you look at the most powerful supercomputers in the world, and not a single one uses a PS3. But many of them use the PowerXCell. (including a former #1, RoadRunner) That demonstrates that this Air Force machine is all for show.