I'm still reeling from the Apple's announcment that they were switching to Intel processors. Whatever Apple may say, I think the only reason is that the AIM alliance (Apple, IBM, Motorola) didn't work out the way Apple had hoped when they started it to make PowerPC chips (which are popular not just in gaming consoles, but lots of military applications as well). The two companies that actually manufacture the darn things have pretty much lost interest in making PowerPCs for personal computers and have often left Apple with egg on its face.
Apple faces a significant short term hurdle - will people buy PowerPC computers now knowing that software support for them may be problematic in a few years? The only bright spot is that Apple has tackled this problem before, when they switched from 6800 chips to PowerPC, and even when they switched from the old System 9 to the new System X.
And finally, the most important question: How will this affect Mac gaming?
As you point out, they handled the 68K to PowerPC transition fairly well, they should be able to execute this one as well. I am surprised they didn't do a deal with AMD.
Cringely has another take that I don't find very convincing.