I'm the test lead for a WPF projec called Prism, it's a WPF Composite Application.  It can be found on codeplex : http://www.codeplex.com/prism

For the next several weeks I'm going to blog on testing a WPF application.  We are plublishing all our automated test cases.

Presently we are using the Thoughtworks White to help write our automated UI test cases for WPF.    The reason for using this instead of going directly to the UI Automation layer is that White has simpliefied some of the complexity of UI Automation.  This allowed us to get up to speed in writing our acceptance ui test. 

Still, as the complexity of our test cases increase and our understanding of the UI Automation grows.  We will probably levage UI Automation layer directly.