For more information check my blog: http://lacckodes.blogspot.hu/2013/05/multitouch-in-wpf.html
In Expression Blend you can use the library without code. Just add IpdsMultTouch.dll to project references. After this you can easily drag and drop TouchManiulatorBehavior from Assets/Behaviors to the control that you can make touchable. Set ContainerControl and add gestures to the behavior. Gestures can be built-in (like scale, translate, rotate) or your own and can be set on properties of the behavior. More gesture can be added.
2013, lacc