This is a first step, but it provides a source code solution in .NET to render 3D objects over a live webcam video feed.
To get it running just make sure you have a webcam with a clean image, .NET 2.0 and Visual Studio, the WPF (Windows Presentation Foundation) installed, and DirectShowLib. These are all linked from the above link.
I really hope this can be expanded on and that Casey does not mind me referencing his code because the more interest there is in this, the faster/more practical it will grow and become. We don't see really exciting creations like this in everyday life very often, but hopefully this will establish itself.
Btw, one I've not checked out properly: http://sites.google.com/site/augmentedrealitytestingsite/
- DirectShow API on WikiPedia: http://en.wikipedia.org/wiki/DirectShow
- DirectShow Article at CodeProject: http://www.codeproject.com/KB/directx/directshownet.aspx
- TotalImmersions AR video: http://video.google.com/videoplay?docid=6523761027552517909
- Also, a skeleton C# AR app: http://sites.google.com/site/augmentedrealitytestingsite/