ZAM 3D ™ from Electric Rain is a new 3D XAML Tool for Microsoft Windows Vista application development, and a CTP is available for download .
ZAM 3D fits into the designer-side workflow by complementing Microsoft Expression Interactive Designer. The idea is that a designer uses ZAM 3D to easily create 3D interface elements, models, controls, styles or layouts. Then the designer exports the 3D assets to XAML markup with a single click without any need to write, or even understand, the complex markup that goes into building a WPF 3D scene. Now the 3D assets are easily added to an Expression Interactive Designer project using the Project > Add Item... command.
You can see some stunning examples of ZAM 3D assets  in use in Windows Vista applications on Electric Rain's website.