Astrophysicist Replaces Supercomputer with a Cluster of Eight PlayStation 3s
wired.com
wired.com
I do believe that it is getting harder to think of how to make money on things like that because the set of applications that are (as a whole) processor-bound are getting ever smaller. It seems that everything (except videogames, of course) is either memory-bound or IO-bound.
Outside universities, the only people that could be interested in PS3 clusters would be crackers that want to break passwords using brute force.
Suddenly, getting a PS3 got a lot more interesting.