A boutique semiconductor design company, P.A. Semi specializes in super-low power PowerPC processors. It boasts a rock-star design team littered with Itanium, Opteron and UltraSparc veterans, led by Dan Dobberpuhl, who was among the lead designers on Digital Equipment’s Alpha and StrongARM chips. And in February of 2007, P.A. Semi uncrated its PWRficient 64-bit multicore processors, 2-gigahertz ARM chips that consume just 5 to 13 watts of power, making them 300% more efficient than any comparable chip.

An impressive chip. Question is, what does Apple want with the impressive little chip shop that made it? Perhaps the same thing it was looking for in 2005 when it first approached the company about a supply deal. That agreement never panned out and Apple subsequently signed up with Intel (INTC) and made transition to X86 chips. The switch has gone well. So well, that it seemed almost a foregone conclusion that Intel’s new line of Atom processors would end up in everything from the next generation iPhone to that mythical iTablet, Apple gaming console and next-gen Newton.

But perhaps that’s not the case. Perhaps Atom’s not quite to Apple’s liking? Perhaps, as word on the street has it, it failed to produce the kind of battery life that Apple wants for its ultra-portable designs. Perhaps Apple just wants its own in-house processor design team, one it could use to push its own technical innovations into the market.

Or perhaps P.A. Semi’s working on a new chip so insanely great that Apple CEO Steve Jobs felt compelled to acquire the company? More to follow when Apple reports earnings later today.