I do love having a developer community out there. We've had lots of requests for direct WPF integration of VE3D, and we've certainly wanted to make it part of the story... and then someone else just goes and does it. Marc Schweigert called this to me attention yesterday. Infostrat has taken VE3D and wrapped it up in a WPF control that you can just drop right into your XAML, which is precisely what folks have wanted out of it.
But it gets better. Infostrat has also put this project, including the source, onto CodePlex under LGPL. I've downloaded the source and built myself with no problems. You just need VS 2008 and .NET 3.5 SP1. The central problem and the trickiest part for most folks is how to efficiently get VE3D to composite into the rest of the WPF app, and they've done a good job. For more sugar, they also have a Surface version with multi-touch support.
Many thanks to Josh Blake, the primary developer on the project, and the Infostrat team. Have fun!