An excellent series on WPF by Josh Smith is available on CodeProject:

• Part 1 (XAML): Learn about XAML and how it is used in WPF applications.
• Part 2 (Layout): Learn about layout panels and how they are used to construct user interfaces.
• Part 3 (Data binding): Learn how WPF data binding works and how it can be used.
• Part 4 (Data templates and triggers): Learn how data templates and triggers work and how they can be used.
• Part 5 (Styles): Learn about how UIs can be styled in WPF.

This series really breaks down some of the slick things you can do with WPF, and does so in a very simple and lightweight tutorial.  If you really want to know more, you'll need to do further research, but the basics are here.