@notnotme: Apple did buy PA Semi apparently to gain microprocessor design expertise, but analysts have concluded Apple did NOT use its PowerPC based design. Instead they concluded Apple used a a Samsung Hummingbird core based on an ARM Cortex A8 core. See http://www.eetimes.com/electronics-news/4200451/Apple-s-A4-dissected-discussed--and-tantalizing
Chipworks has posted a floorplan of the A5 showing the main IP blocks.
Thanks for posting this link. If I'm not mistaken, the upgrade from one Cortex A8 to two A9 cores was pretty much expected, as was the Imagination Technologies GPU.
As the chipworks blog writer said, "quite a lot of horsepower!"