The good folks that created the WPF/E SDK and documentation have a blog and it is a great source of information and samples. If you're going to be doing any WPF/E development in the coming months, this is a great blog to subscribe to.
Some highlights include:
- A great overview of the WPF/E browser plug-in and how the XAML DOM relates to the HTML DOM
- Information about updates to the WPF/E quickstarts. The quickstarts are an excellent way to learn about vectors, text, animation, media and mouse input in WPF/E all with interleaved live samples.
- A walkthrough for creating reflection effects in WPF/E
- A Virtual Earth / WPF/E mash-up with sample code and a walkthrough for each part of the sample.
Here's a pic of the Virtual Earth mash-up (click to run the sample):