From the sounds of it, in reference to the andy tech article and now john carmack himself, multi-core processors is not the way to go. Not only will it be more difficult and time consuming then a single core cpu, but it doesn't look like it will be as powerful as a p4 3.8mhz, or a amd 64 single core cpu.
Theoretically a multi-core system can produce great yields in gaming, but realistically is looks like it is not the case. I can understand why ms went with it; on paper it looks powerful, and the price is cheap. But what we do not need is games that require more resources and development time.
I wish ms would have gone with the more powerful single core cpu, preferably the amd 64. But then they would have had to license the cpu.
But thats just my opinion, what do I know?