I read Petzold's blog from time to time and I realized recently he has posted a lot of good 3d content.
and finally it's coming WPF 3d book by Petzold.http://www.charlespetzold.com/blog/2006/12/270206.html
5-6 years ago, there's a trend to have app written in irregular window, layered window, pixel opacity or different chrome. Then came a wave of products doing just that. I think what's coming next (in my own opinion) is the application have multiple layers and 1..n layer that display 3d visuals. For example, a TV app with tv controls in another layer in a Viewport3d floating in 3d or even animating a bit :-)
can't wait for his 3d book ...