Actually it won't be a good thing if Microsoft did the same thing. For starters, big features that need a lot of design and development (think Windows 8 GUI) take much more than a year. Also Windows needs to be tested across a lot more hardware and much bigger software ecosystem than OS X, so longer alpha and beta cycles are needed. They already release minor upgrades via service packs. I would rather have a solid OS like Windows 7 once in 3 years rather than an unstable OS every year.