I noticed that cycles does not render the reflection of lights, any lights. It just creates fake specularity for glossiness, I mean, if you render a huge area light in front of a perfect reflection, it will be invisible. You will only see a fake of it with some glossiness.
Because of that, I always use a mesh with emit shader. It works great. But I want to mix cycles with Blender internal. I still want cycles to have the reflection correct, but I wish to share the same light for both of them, since Blender internal does not support mesh lights.
For that I could, either make the area light visible to reflection in cycles, or make the mesh to ONLY appear in reflection, not in the illumination of the scene (the area light would do that).
It is just not yet implemented feature, Area light in Cycles sampled only by direct light probe, as point or sun lights, no actual geometry rectangle to sample by direct ray hit. You need to ask to Brecht, or convince other ppl to program it, it not that hard IMHO, add extra quads with emission material and update if original Area lamp changes.