On the speculative note... check out this PDF for the GeForce FX Go series:
GeForce FX 5600 & 5200 Go PDF
Not only do they mention the fact that it's compatible with OS X (and even 9, oddly enough), one of the promo shots below has a 15" PowerBook (albeit a titanium). Something tells me that these chips may be used in the next PowerBook update.
Just for kicks, here's a "dream" config for PPC 970-based, aluminum PowerBooks if they were released sometime this summer:
12" PowerBook
- 1 GHz PPC 970
- 256 MB of DDR333 memory
- 32 MB GeForce FX 5200 Go graphics
- 60 GB hard disk
- Combo or Superdrive options
- Bluetooth built-in
- Airport Extreme ready
15" PowerBook
- 1 GHz PPC 970
- 256 MB of DDR333 memory
- 64 MB Mobility Radeon 9600 graphics
- 60 or 80 GB hard disk options
- Combo or Superdrive options
- now includes Bluetooth
- Airport Extreme card included
17" PowerBook
- 1.2 GHz PPC 970
- 512 MB of DDR333 memory
- 128 MB GeForce FX 5600 Go graphics
- 80 GB hard disk
- Superdrive
- Bluetooth
- Airport Extreme card
Those would be great, of course... I won't even dare to speculate on prices though, even if the details I gave are (miraculously) spot-on. I do admit that predictions of an 80 GB hard disk and a 128 MB mobile graphics chip are optimistic, but they both have a basis in reality (as each is likely to be available by the time Apple would do such a thing).
Believe it or not, another piece of optimism I have is that Apple may well introduce the PPC 970 into the PowerBooks first, or right alongside the PowerMacs. Jobs called this the "year of the notebook" and may have been implying more than just the introduction of the 12" and 17" PowerBooks using G4s. Of course, he could have just been alluding to a major iBook revision, but who knows?