> like IBM did with their BlueGene by building a new system
> architecture around an array of simplified PowerPC 440 cores.

Just to annotate, recent BlueGene system is built around 8192 "Power BQC" processors at 1.6 GHz each, which I assume have PPC A2 cores (like PowerEN).

http://www.top500.org/system/11073

> the Cortex-A15 that will over time bring:
> • Speeds beyond 2.5GHz+

ARM says "1.5GHz – 2.5 GHz", not "beyond 2.5GHz+".

http://www.arm.com/products/processors/cortex-a/cortex-a15.php?tab=Performance

> 14,000+ DMIPS

14,000 DMIPS with how many cores at what clock frequency? Without these information that figure is of almost no use.