It looks like this project is part of a goal similar to that. According to a blog post, Emscripten is an attempt to port a 3D game engine to the web:

http://syntensity.blogspot.com/2010/08/emscripten.html

The game engine's website is here:

http://www.syntensity.com/

Hopefully this experiment works out - both of these projects looks very interesting!