While reading in the news sections about FAA's list of 'encounters,' there was mention of one UAV having a transponder. First, let me say that the list read as sightings to me, not encounters. But, the UAVs were in flight airspace. This makes me wonder if the FAA might insist on transponders on commercial UAVs. My question: Does anyone know how small transponders can be made and what the cost might be? Besides regulation, maximum altitude, etc., this would make sense. Therefore, the FAA won't ever think of it, right?! Your thoughts?