Not sure how hard it would be, it would be necessary for me to have a 3D display myself to be able to properly test it, and I don't own one. Also, not sure how many people would actually be using it. But I agree, it would probably be pretty cool.
I did a quick search now and found this:
"nVidia 3D Vision provides stereoscopic 3D effects for most 3D games based on Unity, without needing any plugin. It does that by "expanding" the camera at the driver level (DirectX) while Unity is rendering the scene."
"not all effects in Unity are guaranteed to work improperly: cascading shadows and certain shaders have been known to work incorrectly."
So perhaps it might work already..?