Thanks to Tom Archer (the content strategist for the WinFX parts of MSDN) and Parimal Deshpande (the marketing manager for Windows Presentation Foundation), we now have the PDC hands-on labs available for Windows Presentation Foundation. If you're a kinesthetic learner, you'll appreciate the ability to experiment directly with Avalon by practising real-world coding problems with these examples - they're a great way to learn how to use Avalon. I'd particularly recommend the styles and templates (PRSHOL07) and data binding (PRSHOL04) labs - in my opinion, much of the power of Avalon is built from these concepts, and getting to grips with them will have a big impact on your productivity with Windows Presentation Foundation.
Incidentally, you can also find the ASP.NET Atlas labs, Windows Workflow Foundation labs and the LINQ / DLinq / XLinq labs available on MSDN in various locations. Pretty well hidden, aren't they? Let's keep them our little secret, dear loyal reader!