At the Future in Review 2007 conference in San Diego, California Microsoft executive Ty Carlson talked about the future of the Windows operating system. He claimed future versions of the operating system will be "fundamentally different" in order to take advantage of multi-core processors.
Carlson said Vista was designed to run on one, two maybe four processor cores but that future versions of Windows will need to be designed for PCs with eight, 16, 64 and even more cores.
Carlson is tipping his hat to the fact that little growth is expected from straight MHz scaling of single CPU cores over the coming years. Multi-core is the only way to go (for now), but Microsoft isn't exactly behind the times. The Windows kernel has supported multiple processors since the first release of NT (which for marketing reasons was called version 3.1) back in 1993. The NT kernel can allocate various processes and threads to different CPUs, and the maximum number of CPUs that it supports is generally an issue of licensing, not technical capability. (There is a hard limit, however, on NT systems: 32-bit Windows can have only 32 total processor cores, and 64-bit Windows has a 64-core limit, no matter how many physical processors are in the system).
It only makes sense that as the multi-core scene matures, so will Microsoft's embrace of it. Whether or not this embrace will result in something "fundamentally different" is not particularly clear, and given that Carlson is more of a marketing person than a technical one (he previously held the position of manager of the rapid deployment program), there's always the possibility that "fundamentally different" means nothing more than "different." Still, let's give him the benefit of the doubt.