Chuck Jazdzewski has a decent two-part primer on XAML on his blog.

Today I begin a tour of XAML. As Chris said, I have been part of development of XAML. I came fairly late to the game, however, more closely to the end of the Avalon development cycle than at the beginning, and XAML was already fairly well defined when I arrived. I did work to push some changes into the language, primarily driving consistency and regularity in the language as well as put developing features that support versioning and extensibility. We will cover some of those things in our tour, but lets start at the beginning.

The first question we will cover in our tour is what is XAML anyway? Simply, XAML is an XML based object initialization language. Its job in life is to create a tree of objects...

Part 1

Part 2

Nicely done!