Excellent intro into Silverlight developing

Silverlight developing using .NET
must read article.

What about 3D in WPF

This are much much better in this department, check this link:
http://blogs.msdn.com/tims/archive/2006/02/08/527850.aspx

3D in Silverlight

Microsoft dropped few chapters from XAML regarding 3D, but what was left is enough for simple 3D implementations like this one:
http://www.dolittle.com/blogs/einar/archive/2007/05/19/3d-in-silverlight-1-1-alpha.aspx