The technology building blocks exist to do this. A transponder, for example, transmits basic aircraft data regularly. One might craft a system using Inmarsat or another satellite network. Trucks in the U.S., as another example, can use Qualcomm's Omnitracs satellite system to send truck positioning information, cargo temperature, speed of the truck, etc. with a little bubble antenna on the roof. Ideally you want to get countries together on this (frequencies, transmission standards, etc.), and that would be tough. I'm just talking technology here. The pilot's privacy concerns are real and should be addressed in any such system.