After adjusting the export_multi.py script to export light emitting objects and a sun/sky system, we can render the bedroom scene with mental ray using MDL materials (see NVIDIA's technical documentation about their Material Definition Language):
Let's just have a quick look at parts of the resulting bedroom.mi file (mental ray specific scene description):
The intensity of the sun light can be controlled by adjusting the rgb_unit_conversion color parameter.
The intensity of the light bulb is dependent on the color of the physical_light shader. Later this light emitter will be replaced by it's MDL counterpart, but for now that's how it works.