Are you intrigued by multi touch? The Windows Engineering team just posted a great article on how Touch was implemented in Windows 7 and on how software developers can tap into this: http://blogs.msdn.com/e7/archive/2009/03/25/touching-windows-7.aspx#comments
The developer from a Windows team point of view use the WIN32 API. Of course most of you use .NET. There are also a bunch of resource available for you already.
Check out these labs to find out how you can use Windows 7 touch with WPF 3.5 SP1: http://code.msdn.microsoft.com/WindowsTouch
This WPF 4.0 session from PDC shows you what you can expect next: https://channel9.msdn.com/pdc2008/PC03/