APIs in WPF4 plus Surface Toolkit for Windows Touch make building common touch scenarios easy. However, implementing many of the same touch scenarios using WPF3.5SP1 or Silverlight 3/4 involves writing a fair bit more code. Furthermore, touch APIs across WPF4, WPF3.5SP1, and Silverlight are different. Goal of this project is to simplify building common touch scenarios when using WPF 3.5 SP1 or Silverlight 3/4 by using Expression Blend Behaviors to provide a consistent way to implement these scenarios across WPF & Silverlight. Expression Blend Behaviors can be used within Visual Studio without a dependency on Expression Blend with Expression Blend 3 SDK. You can also find more Expression Blend Behaviors.
More info: Multi-Touch for everyone