Evidence mounting: Windows 7 going modular, subscription
When Windows 7 launches sometime after the start of 2010, the desktop OS will be Microsoft's most "modular" yet. Having never really been comfortable with the idea of a single, monolithic desktop OS offering, Microsoft has offered multiple desktop OSes in the marketplace ever since the days of Windows NT 3.1, with completely different code bases until they were unified in Windows 2000. Unification isn't necessarily a good thing, however; Windows Vista is a sprawling, complex OS. A singular yet highly modular OS could give Microsoft the best of all possible worlds: OSes that can be highly customized for deployment but developed monolithically. One modular OS to rule them all, let's say.
Full story at ars technica.