Interestingly, a PS3 miner is just what I've been working on. I wrote it largely to teach myself how to program for the Cell Broadband Engine, but it's been an interesting experience learning about Bitcoin as well.

I don't imagine what I've written is completely well optimized yet, but my current estimate is about 7.5 Mhash/s across all six SPEs. I also don't have a good statistics gathering method yet, so this may not be accurate.

The mining architecture is a Ruby front-end (JSON RPC client) with a custom extension library to run the SPE contexts, and native SPU code for the back-end mining. I couldn't get Bitcoin itself to run on the PS3 because Bitcoin is heavily dependent on the little-endian environment and the PowerPC on the PS3 is big-endian.

I may release the code at some point if there is interest. I'll let you know if I manage to improve on the performance.