I hate to burst your bubble however the good old IBM processors have had their days of glory, well for desktop computers at least. The Power6 plus the Cell processor on paper look very cool, but you have to factor in that they are largely untested in a consumer enviroment and I don't think even Apple would put something of that sort in a Mac for all us dumb bunnies to be the control group.
The future of desktop processor I have to say belong to AMD, Intel and to a lesser extent VIA. Power6 you might see in high end servers, plus consider the Power6 looks like it's going after the Silicon Graphic and Sun Box server markets which doesn't really effect Apple in the first place.