I just posted a screencast showing how to wire up UI elements using Blend.  The general premise is that databinding in WPF is about more than just data; it also allows you to connect UI properties, like wiring a slider up to a progress bar. Blend exposes this is a very useable way, once you know your way around.  I also use some cool styles from this Charles Petzold article and show how, in Blend, you can extract a style and template from a piece of XAML to be reused in other parts of your application.