While at the LAUNCH event in Silicon Valley, Daniel Lewin, the corporate vice president for Strategic and Emerging Business Development at Microsoft has hinted that the much-anticipated Windows 8 operating system will arrive sometime in autumn 2012.
Lewin's cvasi-revealing statement was this: "... if you look at the crystal ball and just say what happened in the past is a reasonable indicator of what our forward looking timelines will be and just speculate - we've made the point about having a developer conference later this year, and then typically we enter a beta phase, and then in 12 months we're in the market, so let's make that assumption."
Microsoft previously announced that Windows 8 will be detailed at the BUILD developer event in September, so going by Lewin's time line, a beta of the upcoming OS will arrive a bit later, probably in October. Add around 12 months and voila - we'll have Windows 8 in full, working both on x86-based systems and ARM-powered devices. Don't mark anything on the calendar yet through since things aren't final.

Source :tcmagazine.com