We recently did some green screen composite tests for an upcoming project. We utilized our 530sq foot studio and our (very large) green screen.
Once the green screen was keyed out, we developed a 3D matte for the background image. The 3D scene was lit to match (roughly) the lighting in the sound stage. The final shot ended up being very convincing. This was a true success considering we put the whole shot together in under 2 days. The imaginable possibilities are limitless. We will be posting the final composite video soon.