I have seen it recommended for high powered LEDs in threads just like this one. More than once. This was based on the heat transfer and the fact that you can remove the led's much easier than you can with epoxy.

I also just found a thread abount the AS adhesive compared directly to thermal tape at overclockers cafe. The tape wasnt too far behind in my opinion. Especially for this application.

I guess I will just have to see for myself.