This is pretty cool, and worth considering if you want a designer to implement your front-end, rather than a coder using a designers erm… designs.
http://www.tulrich.com/geekstuff/gameswf.html
Gran Turismo uses a similar style of Flash based UI, and got some great feedback on it, so this style of UI dev being used commercialy.
I’m sure the code could be changed to tag the background to have transparent bits ( eg using a PNG ), you could let the 3D engine show fancy effects behind the UI etc.
Mal