WPF 4.0 support touch events and related inputs. These events are implemented through UIElement, UIElement3D, and ContentElement classes. These classes are the base classes for most of the WPF control. That means we can build touch screen enabled application using same code. The only thing we need to do is implement touch related events.

To build touch enabled applications, you will need Windows 7. Here is good startup tutorial on building touch enabled applications using WPF.

Walkthrough: Creating Your First Touch Application

Silverlight also supports touch events. Here are two good articles:

Touch events in Silverlight for Windows 7 mobile application: Part 2

Touch events in Silverlight for Windows 7 mobile application