We've heard an awful lot about a Windows tablet OS this past year, with stirrings of a 2012 launch -- heck, even Steve Ballmer's fanned the flames of speculation -- and now the rumor mill's been set in motion with word of an impending preview expected next week. According to Bloomberg, three sources have confirmed Microsoft's plan to flaunt the much-anticipated UI, possibly at upcoming appearances at AllThingsD and Computex. The showcase is supposedly set to run the touchscreen-enabled software on a Tegra-equipped machine. We'd previously reported on stirrings of a June demo. Considering all the evidence that's stacked up over the past few months, we'd say 2012 is looking like a rather practical target.