A number of universities and governments use PS3s for analytical computing, but with mainstream x64 processors coming with 8, 12, and more cores, and mainstream graphics cards carrying hundreds of stream processors, the Cell (as it exists in the PS3) isn't much of a win apart from the price.
The price in fact is a problem and probably one of the reasons for their decision. Sony looses money with every PS3 they sell, they only make profit with games. All the Linux powered PS3 clusters coming up without games being sold ruin their business case.
