ARM today has made the announcement many have been waiting for, the availability of their Quad-core A15 CPUs based on the 28nm die process. The Cortex-A15 hard macro processors are floating-point monsters, running at 2GHz and cranking out 20,000 DMIPS while sipping electricity at the same rate as the dual-core Cortex-A9s.

A large part of that efficiency gain comes from the die shrink between the Cortex-A9 and the Cortex-A15, the A9 was built on a 40nm process, the same as every other mobile CPU sold last year, from the iPhone 4S to the Droid Incredible 2.

The shift to a 28nm process in the A15 takes advantage of one of the few "free lunch" aspects of physics shrinking the transistors means less electricity is lost as heat, so you clock cycles get faster and more efficient, which is win-win for end users. Of course die shrinks are incredibly hard engineering feats, so that "free lunch" is awfully expensive to "cater".