It would require a compiler that takes advantage of the SPE units to run well. IBM has >one (no idea about the cost) used for professional development. It is not a simple chip >to program for and without extensive work done on parallel processing it doesn't perform >up to potential. Once that work is done on the software it should outmatch any PC >hardware.
-In HPC-circles (the people with the largest computing iron...), the Cell processor has stirred quite some emotions. The relatively unknown Mercury Computer works with IBM: http://www.mc.com/cell/products/view/index.cfm?id=5&type=Software
When the Cell is able to produce 64bit double precison floats it's very likely that'll it replace a lot of big iron. IBM has included it in its proposal for this coming round of DARPA HPC competition.
AvS