IanG's First Look at 3-D Support in Avalon
MSDN just published an introductory article on 3D support in Avalon by fellow blogger Ian Griffiths of DevelopMentor. The article is liberal with screenshots and provides a good mapping between the high level concepts and the Avalon object model. It's a great way to get yourself oriented to the platfrom and includes a link to Ian's .x file to xaml convesion tool I mentioned earlier.