Windows Phone 7 Series UI Design & Interaction Guide
Videos of MIX10 Windows Phone sessions
Getting Started With Windows Phone 7 Series Development
Tip & information:
protected override void OnManipulationStarted(ManipulationStartedEventArgs args)
{
Color clr = Colors.White;
if (args.OriginalSource == txtblk)
....
Original Source tells you in which element finger manipulation has been started.
"Currently, no production devices have been released. As I understand, the devices will start hitting the market Q4 2010 before Christmas" by Chris Bennett.