I think apple should look into using that new Cell processor IBM, Toshiba, and Sony are working on. It is the only true multicore processor in procution. It will have something on the scale of ten cores in each chip. Compare that to AMD and Intel's rinky dink dual core phlim phlam. I say phlim phlam because the Intel Chip isn't really a dual core, but two dies on one chip. I see true dual core similar to AMD's chip. Both cores run off the same bus, unlike Intels, and the Chips can use shared onboard cache. this reduces task intervals and drastically speeds up processing. Intel's is more like Hyperthreading to the next level.
Cell is not fully generally. It is more like the old Cray vector engines. Ridiculously fast for certain narrow domains, but dog slow for a ton of others. It would be a pile of stinky poo for a lot of very standard applications.
The point of a good CPU is that it can do everything you can throw at it reasonably well. Things like Cell, DSPs, FPGAs, etc are more useful as co-processors unless you only plan on running a single type of code (like graphics intensive apps). Speaking of which, one of Cray's current systems does bind FPGA coprocessors to Opterons. Pretty sweet.
Cell is not a new idea. It is a rehash of a very old one. There is a reason we don't use architectures like that for general purpose computing.