It seems there have been rumors in December 2009 that Nintendo's next generation system might be based on IBM's 476FP core. Judging by the little information we have regarding IBM's involvement, that would make some sense: it seems Nintendo contracted them between late 2009 and early 2010, and the 470 series was the most efficient core they had at the time.
The 476FP, presumably used in a 16 core configuration, is actually quite impressive. It's not exactly very fast, but incredibly efficient. It's a 32bit PowerPC core, out of order and highly modular, with a really short pipeline, supporting SIMD and DSP instructions. It draws about 2W while achieving around 4GFLOPS (double precision) at 2GHz - per core. It's currently IBM's latest and greatest, at least until the A2 ships.