The decision to center the iPhone design around a chip that Apple could own marks a significant strategic choice by Apple Chief Executive Steve Jobs, and is aimed at ensuring Apple can continue to differentiate its flagship phone as a raft of competitors flood the market. According to a source affiliated with the chip company, Jobs and Senior Vice President Tony Fadell led the tiny group of executives who spearheaded the acquisition, which included negotiations that took place in Jobs’ home.

P.A. Semi and Apple are no strangers to each other, as the chipmaker was reportedly courted by Apple to possibly provide Power-based chips before Apple finally settled on the switch to Intel.

Recent rumors have suggested that future platforms based around Intel’s forthcoming Atom processor might be targeted for the iPhone, but Apple’s acquisition of P.A. Semi suggests that this may not be the case.

The 150-person chip company, P.A. Semi, was founded in 2003 by Dan Dobberpuhl, who was a lead designer for the well-regarded Alpha and StrongARM microprocessors developed by Digital Equipment in the 1990s.

P.A. Semi apparently has the chops too. Last year the company announced a 64-bit dual core processor that it claimed was around 300% more efficient than its nearest opponent. Products featuring a P.A. Semi engineered chipset wouldn’t hit shelves for at least a year or so. Blam over at Giz thinks that Intel and ARM are probably less than thrilled at this news. He also thinks (and I do too) that it’s logical for Apple to work in its own internal hardware in order to produce better devices. Here’s to speculation. But for Steve it’s likely this is all part of the plan.

The buy has come as a surprise to many analysts, who expected Apple’s headline-grabbing relationship with Intel to see future mobile devices using the chip company’s own Atom platform, itself a low-power design. It’s been suggested that Apple’s acquisition is in part to further seal off the potential of upcoming products leaking, which has historically plagued the run-up to each eagerly-anticipated launch. Negotiations took mere weeks, although prior to the Intel deal Apple and PA Semi were in talks which then fell through.

This doesn’t mean, of course, that we’ll see a PA Semi chip in the 3G iPhone; the deal is too recent for that. But given the ongoing rumors of an Apple UMPC - possibly in the form of a larger, maybe QWERTY-equipped iPod Touch - and the iPhone’s further blurring of the smartphone, MID and UMPC niches, it’s unsurprising that the company is looking for highly efficient mobile processors. According to Forbes, Apple plans to continue to supply and support existing PA Semi customers, but keep future chips exclusively for itself.