I downloaded a model from blendswap.com and when I rendered it I got this -
The scene is made up of: the model, plane, hdr map and hemi lamp that is lighting the object. As you can see, the ground plane is not effected by the light. Its node setup is this -
Why is the plane not effected by the light? I even replaced it with other lamps but the effect is the same. Why? How is that done?