Right now Vista has fizzled, XP is still around but antiquated and Macs are overpriced, overhyped and generally disliked by people outside the cult. If you could buy an OS from Apple separately, you might find takes but as long as Apple tries to fuse its hardware to software monopoly, the market share of Macs will keep falling because buying one requires just too much of a commitment. Meanwhile Steve Jobs appears to have turned its back on the Mac and is increasingly focusing on personal electronics like the iPod and the iPhone and the miserable Apple TV (How did they not call it iTV?)
It’s a perfect window for a new OS. Not simply another flavor of Linux but something that genuinely changes the way people can use their computers. The latest computers come with huge amounts of resources that are vastly underutilized by Vista, which hogs resources and is about as clumsy as is humanly imaginable. Linux flavors are fine for people looking for control and customization but do not resonate with average users. It’s simply too many options and too much confusion.