The parent here makes it sound like you should be able to just write a few lines of code and set a compile flag to have your program start using the SPEs on the Cell. That's completely untrue - you'd need to write some very specific, very custom code to use them, as they're basically just very fancy DSPs with regards to C coding.
As a point of reference, no one's ported x264 to use the Cell for encoding, and that's the sort of application that the Cell is supposed to be very good with. IIRC, part of the issue was that each SPE only has 256kb of cache on it, which is rather marginal for high resolution rendering (you can't fit a whole 1080p frame into the SPE).