Microsoft Surface Manipulations and Inertia Sample for Microsoft Silverlight available for download!
Download link: http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=4b281bde-9b01-4890-b3d4-b3b45ca2c2e4
The manipulations and inertia processor classes allow graphical user interface (GUI) components to move in a natural and intuitive way. Manipulations enable users to move, rotate, and resize components by using their fingers. Inertia enables users to move components by applying forces on the components, such as flicking the component across the screen. The contents of this sample are covered by the Microsoft Surface SDK 1.0 SP1 license agreement, with any additional restrictions noted in the Readme file. The purpose of this download is educational use only and is made available "as-is" without support.
Also interesting: The Silverlight Multitouch Input Documentation on MSDN.