During one of our past bug-bashes, I worked on the very popular (but simple) FreeCell game. One of the cool things I like about WPF is the ability to keep the business logic separate from the user interface - the biggest benefit is you can pull out Expression, do all the graphics, and then wire-up the code later. Though this example has very little interactivity, it shows how easy it is to achieve this. All the UI was done completely in Expression and all of the code was written in VS (sorry for the poor code quality - I only had a litte over an hour to write it!). Also, you will notice the use of another custom control to layout the various cards in a stack - they (WPF) have made is so very easy to extend the functionality of existing panels/controls. Source can be downloaded from here.