IBM really blew it with the PowerPC
Losing Apple as a customer has got to count as one of the bigger blunders in IBM's history.
My guess is that this marks the start of a slow and painful end to the PowerPC architecture. Rather a shame. Looks like it is going to be x86, and pretty much everything else is fading out. Yes, I know that IBM gained a huge design win in Microsoft's next X-Box. By itself and in the long term, this does not count for anything. Microsoft can just as easily switch away from PowerPC is their next iteration. Giving up on the desktop market seems to have marked the beginning of the fade-out for the other diminished processor lines.
One notion that might have more legs is a Sun/Apple alliance. Not sure how the current Sun CPUs compare to the current generation Intel chips. Realistically if the individual CPU cores are roughly equivalent to 1-2Ghz x86 CPUs - that should be more than good enough for the majority of desktops. If Sparc multi-core CPUs can be fabricated with similar or better net throughput, power consumption, and cost as equivalent x86 offerings, then they could prove competitive.