We're live from Microsoft Windows president Steven Sinofsky's keynote at D9, and there's something rather exciting on stage -- a pair of experimental Windows 8 dev boards running an OS that looks very much like Windows Phone 7's Metro UI. All Things D actually sat down with the man earlier today and got a sneak peek at what to expect starting with the live tiled screen you see above -- and yes, like Windows Phone 7, this OS is designed for touch.

There'll be two kinds of applications for Windows 8, one that runs in a traditional desktop, and the other pseudo-mobile apps based on HTML5 and Javascript, but both environments -- rather, the entire OS -- have been designed from the ground up for touchscreen use. Keyboard and mouse will still be options for both sets of programs, but there are multiple virtual sets of keys for different form factors, including a split keyboard for vertical slate use. Multitasking is simply a matter of swiping running apps into the center of the screen, and you can pull windows partway to "snap" them in place alongside other windows -- even mixing and matching traditional desktop programs with web apps simultaneously (like Twitter alongside your spreadsheet). There's a new version of Internet Explorer 10 (which runs Silverlight) and an app store built into the touchscreen interface, along with integrated services like Office 365. Microsoft says the new OS will run on laptops, tablets and desktops when it appears -- whenever that might be.

All Things D didn't have any details on when we'll get pricing or availability, but we're looking at some Intel Atom-based demo units on stage right now, and Microsoft says it will have ARM designs (the OS will support NVIDIA, TI and Qualcomm) viewable on the Computex show floor, and more will be revealed at the Build Windows developer conference in September. We should note that "Windows 8" is just a codename for what we're seeing here -- "we'll figure out the real name in due time," Sinofsky told the crowd -- but we don't see much harm in calling it Windows 8 for now.

Update: Video after the break!