Okay, so I wanted to get this post in under the wire.
From the reports out there, and other blog posts, it seems that there's not been any sort of confirmation that Apple is going to be using the x86 architecture, just "Intel chips". Also, I was told I was definitely wrong about Apple swapping over servers first - that they're going to do some inexpensive box first, either a mini-type machine or a tablet (wouldn't that be nice). My thoughts about the Servers changing first is that there would be less software to have to port, but it doesn't look that way.
So that means one of two things could happen. First, as Kottke said, Apple has a bunch of the IP around the PowerPC platform. They were part of the three that developed it a decade ago with Motorola and IBM. So they could maybe give the rights to Intel to make PPC clones, though obviously the internals of the chips could be Intel proprietary tech. Aren't the internals of the newest chips the same sort of multi-scaler RISC stuff we see in PPC anyways, with just a CISC outer layer for backwards compatibility?
The other thought is that Apple goes with Intel's XScale Processors for low-power devices. Maybe a Mac Tablet or maybe a Mini-clone or something else. XScale of course is based on ARM, and ARM is RISC architecture (Advanced RISC Machines) so maybe porting to this chip could be simpler than porting to x86. In fact, maybe combine the two thoughts above and Intel slaps a PPC interface on top of their XScale processors and bam, new CPUs for Apple.
Okay, that's all my thoughts for now. One final thought: as a PowerBook and Mini user which are both G4 chips operating at well below 2Ghz, I can tell you from experience that Apple *definitely* needs a kick in the ass when it comes to chip speeds. I swear, waiting for my Macs makes me want to go running back to my Celeron based Wintel box for sure.
Bring it on Steve!
P.S. Join us in #mobitopia on irc.freenode.net for all the Keynote Update Action!
Update: I was *wrong, wrong, wrong.* Apple's going x86 all the way.
Update 2: Keynote is up. Watching now.