So it's "What I've been reading this summer" time again.
If you want to learn about what it means to do Windows Presentation Foundation, I recommend this book about WPF (aka Avalon): http://www.oreilly.com/catalog/avalon/
It's written by Chris Sells and Ian Griffiths, who I count among those authors who's books I buy without thinking. Which was confirmed after reading this book.
Currently doing WPF training, I also recommend this book to all my students.
O'Reilly also has a more of a reference book called XAML in a nutshell, which you might like to keep next to you while exploring more about XAML and WPF.