Having thought about this for a while, and heard all of the conspiracy theories about how this is Apple’s latest move to dominate the world, here’s what I think.
There is no master plan.
Steve Jobs got backed into a corner by IBM, because IBM wanted Apple to put more money into the PowerPC chip line, which IBM is not terribly interested in keeping alive because, frankly, Apple doesn’t sell that many computers and the technology’s a dead end. So Apple didn’t pay up, and IBM didn’t produce faster, cooler chips for the laptops that Apple wanted, and Apple was left with two choices: produce no more faster laptops, or move to another chip vendor. Intel is the obvious choice, as the largest-and-not-cheapest vendor. Intel’s a little pissed off at Microsoft, and they’ve been getting some heat from AMD (despite continually producing better but not cheaper technology, IMHO). Porting OSX to Intel or anything else is actually laughably easy, because all along, it’s been built on top of a Mach microkernel architecture which is designed specifically for this.
So Apple dumps IBM, who doesn’t really care because they’ve got Sony’s business for the new Cell processors and the PS3 is going to way outsell the Mac any day of the week. Apple will sell, what, 5 million Macs this year? Sony sells that many PS2s in two months. Intel gets a little coolness factor for selling even more of their incredibly popular chip line, and Apple gets their dual-core Pentium M laptops.
Microsoft continues to dominate whole industries through sheer obstinacy.