A new Mobile PC form factor.  Full Windows functionality with an enhanced touch screen, pen and keyboard input.  UMPCs combine the power of the Microsoft Windows XP Tablet PC Edition operating system and other innovative new technologies from Microsoft and its partners, making them more mobile and simpler to use than previous mobile computers. For example, the new, pre-installed Microsoft Touch Pack for Windows XP software optimizes the touch screen user interface for UMPCs to simplify navigation and ease-of-use while on the go. The Touch Pack’s customizable Program Launcher organizes software programs into categories, and uses large buttons and icons to make it easy to find and open your favorite applications. The Touch Pack also includes a thumb-based, on-screen keyboard that’s touch-optimized for easy text input. It also helps improve a user’s portable media experience with the inclusion of the new Brilliant Black for Windows Media Player skin. Touch Pack software also helps keep you entertained with the introduction of Microsoft Sudoku, a highly entertaining touch and ink enabled game. While the first generation of UMPCs will run Windows XP Tablet PC Edition 2005, future models will run on Windows Vista.

http://www.microsoft.com/umpc

http://www.origamiproject.com/3/

http://www.microsoft.com/presspass/features/2006/mar06/03-09Mobile.mspx

http://www.intel.com/design/mobile/platform/umpc.htm

Lastly, Otto Berkes - Origami's Architect gives first look at Ultramobile PCs:  http://channel9.msdn.com/showpost.aspx?postid=169962