Revealed at the press-only kickoff for the Gizmodo Gallery in New York City, the Courier appears to be a dual-screen, hinged touch tablet that is intended to be used primarily as a digital pen and pad.
The screens of this "late prototype" device are seven inches apiece. The home button resides on the hinge and status messages (wireless signal, battery life) are displayed along the edge of the screen. Out back (as in the cover) is a camera.
Until recently, it was a skunkworks project deep inside Microsoft, only known to the few engineers and executives working on it—Microsoft's brightest, like Entertainment & Devices tech chief and user-experience wizard J. Allard, who's spearheading the project. Currently, Courier appears to be at a stage where Microsoft is developing the user experience and showing design concepts to outside agencies.
Microsoft has a history of collaborating with other firms, especially in the E&D division: Zune and Xbox have both gone through similar design processes. (And plans for the Microsoft Store leaked through a third-party agency were confirmed as genuine prototype layouts and concepts.) This video is branded Pioneer Studios, a Microsoft division within E&D that specializes in this kind of work, working with another agency that's a long-time Microsoft collaborator on confidential projects.
While the device supports different types of multitouch input, it's designed primarily to be used with a stylus. One neat interface trick: the space between the two screens -- the hinge -- doubles as a "pocket" to hold items you want to move from one page to another.