I'm surprised there hasn't been vehement public discussion about it.
What is OBD-III?
OBD III is a term used to describe the concept of "remote OBD." Under this concept, vehicle would have the ability to transmit OBD fault information to roadside receivers, for example, through cellular networks. The benefit of such a concept is that a motorist would not have to take their vehicle to a station for an emissions inspection as long as the vehicle is communicating that there are no active emission-related malfunctions. If the OBD II system has detected a problem, the vehicle owner would be expected to have the problem repaired in a timely fashion. Correction of the problem would be verified through the OBD data transmitted after the vehicle has been serviced.
SEMA OBD-III FAQs:
http://lobby.la.psu.edu/_107th/093_o..._questions.htm