Charles Petzold (who many know as the guy they learned about Windows programming from) is a very curious guy. He loves to experiment with things and we have long been the beneficiaries of his curiousity.
One of the things Charles really loves about WPF is it's 3D capabilities. Even though he now has a WPF book out (Applications=Code+Markup), he wanted to write a whole book just on 3D. He's working on that now and it's called Windows 3D (comming out this summer).
WPF/E stands for WPF Everywhere (though this is currently just a codename) and enables WPF to be viewed in a web browser (not just IE either :-)). You can read more about WPF/E at the above link.
Charles has a 3D WPF demo that he put in a web page which you can see here. Note that if you don't have .NET 3.0 on your computer, you will be prompted to download the runtime component (it's painless). It's quite a lot of fun even if it does make him look like a bit of a fathead. (Something that he is not!)