The Microsoft Surface Toolkit for Windows Touch Beta is a set of controls, APIs, templates, sample applications and documentation currently available for Surface developers. With the .NET Framework 4.0, Windows Presentation Framework 4.0 (WPF), and this toolkit, Windows Touch developers can quickly and consistently create advanced multitouch applications for Windows Touch PCs. This toolkit also provides a jump-start for Surface application developers to prepare for the next version of Microsoft Surface. Use it to take advantage of the innovative Surface technology and user interface to develop your own rich and intuitive multitouch experiences for a variety of Windows Touch devices.
You can download the Toolkit here. Note: .NET Framework 4.0 and the Windows SDK are both required, and they are included with Visual C# 2010 and Visual Studio 2010.
After you install the Surface Toolkit and its required software, you can use the following resources to develop WPF-based, multitouch-enabled applications.
You can watch a Channel9 interview below.