Bryant has a few WPF/E animation samples on a recent post and he shows of the XAML for these animations. The most interesting bit I took from this was the comment about learning from the XAML in samples:
"I find it interesting that I seem to learn a lot about what you can do in WPF/E mostly by reading people's Xaml"
This is one of my favorite aspects of WPF/E, it works well with the view source model. Go to Bryant's blog post, view source on the page, search for "new agHost" and look for the XAML file reference. And for samples that have code, the .js files are sent down with the page as well. This really helps enable the organic learning model that helped spread HTML knowledge back in the day.