I have been working with Anthony Handley on a WPF project for the last couple of weeks part time.  We are actually one of the first people I know that are trying to follow Microsoft idea on designer/developer collaboration for developing WPF applications.  The application itself looks great!  We are working through some growing pains as a team.  The most time consuming issue that I have seen so far is rebuilding a screen by removing controls that were used to convey the design to the user.  These controls contained fake data to make it mode clear to the user how the screen shows data.  I had to remove those controls and replaced them with controls that were actually supposed to be used.  This of course broke animations that were tied to old controls.  So far, I think the following is the best approach I came up with.  Here are a few key points.  Designer and developers should work in parallel.  Giving designers a head start does not seem like a good idea.  What is needed is probably a head start for developers instead to be able to create classes that can be populated with data.  That way we should be able to avoid faking the data, and use real classes instead.  This way a designer could create a first draft of a screen.  Then developer can put in data and appropriate controls.  Then a designer could put on finishing touches.  I will keep blogging as I learn my lessons of collaboration.  It has been a fun project nonetheless.