Recently I finished reading "Metal Ray for Maya, 3Ds Max, and XSI" which all things considered was a long read for me. This was part of my ongoing investigation of mental ray which can produce nice results, but is not the easiest renderer to master. The image below is a recent test I created to teach myself about using luminous surfaces with Final Gather. All the light in the image comes from the red, green, and blue stripes which (because the colored stripes are fairly evenly distributed r,g,b) produce an overall neutral light. All objects in the scene are using the mia_material type as a base.