Steve Jobs says that a reason for the move is that Intel chips now offer much more power per watt than PowerPC chips. Which sounds strange, given that Intel chips are encrusted with legacy backward-compatibility baggage dating back to the IBM PC, whereas the PowerPC platform is free of such constraints. Though perhaps, because of Intel's far greater market share, enough was invested in getting around this.
Jobs also revealed that MacOS X had been built internally for Intel platforms for the past five years (which is plausible, given that NeXTSTEP, on which it is based, was sold for Intel machines). Which goes some way towards explaining the somewhat backward choice of architectures: i.e., it's inertia.
Of course, this does not make it any less of a missed opportunity to provide a computing platform on a new, unencumbered architecture. Especially given the PowerPC-like nature of the Sony/IBM Cell CPU, which would (if reports are correct) have been an immensely desirable platform for a new era. (Who knows; perhaps whoever owns the Amiga can resurrect it as a Cell workstation?) And as far as x86 chips go, AMD would have probably been a better choice than Intel. Unless, of course, it's the DRM issue again, and Jobs needs to have a black iron prison in place that the MPAA will sign off on.
And so, the last major bastion of diversity in the world of computers falls to the x86 monoculture, and Apple becomes just another PC manufacturer, albeit one with its own OS. Perhaps in five years' time they'll give up on that as well and switch to providing a Cocoa layer over Windows too? After all, it'd save them a lot of hassle.
I'm certainly beginning to rethink ~$150k of upcoming cluster purchase, if we're going to have to deal with a cluster that's part PPC and part Intel (which is really going to suck, seeing as one's big endian and one's little) regardless.
being able to run linux and windows apps on osx might be nice, however...
"the last major bastion of diversity in the world of computers falls to the x86 monoculture"
i'm not so sure, given darwin could target xen! http://wiki.xensource.com/xenwiki/XenFaq#head-bb579ddda3999d87064a36b7d847fad8e39440ae
also re: AMD they have what, like maybe 5 fabs around the world? intel has dozens...
oh and if laptops are outselling desktops now, it looks like not having a 'laptop chip' seems to have been a dealbreaker for jobs :D
To me it looks more like Jobs throwing a hissy fit, picking up his ball and going home.
BBC says that Apple expects to lose sales over the next few months as people wait for the new chips. I think this a bit of PR spin from Apple who know that many diehards will simply abandon the platform altogether now. After all, why pay a premium to have an Apple logo on your PC when you can buy an unbranded unit and run Linux with an OSX theme.