No, it's not an official one. The guys over at Portable Monopoly were crazy enough to add their own light to the GBA.
Lots of people complain about the GBA's lack of lighting. I personally get along with it. But some people are just crazy enough to add their own light. That's exactly what Adam Curtis of Portable Monopoly did. He took a pair of LEDs and attached them to his GBA and made a forelight. You gotta check this out. It's insane.