This is a very clever way to score high powered CPUs at Sony's expense, it's a wonder Sony hasn't come out with some sort of "patch" that blocked clustering from taking place. Is this the reason that the new slim PS3 has no linux support? Sony finally got tired of taking a loss on all these supercomputer projects?
For those curious, the IBM Roadrunner supercomputer uses a variant of the Cell chip, 12,000 of them in fact. The extended cost per chip is $10,000 (including support hardware). If the Air Force can get their PS3 network running for $300 per chip plus a little extra (say $300 more per station) for support equipment like network, power, and cooling, they will still only be paying $600 per node compared to $10,000 per node the 'old fashioned way'.
Now that's a government spending reduction I can get behind!