What are the recent developments in the satellite-based tracking of aircraft? I find it pretty unsettling that in 2016 it is still not possible to track transoceanic flights using flightradar24 or flightaware, because of lack of coverage.

When the unfortunate MH370 accident occurred, I stumbled upon news of the British company Inmarsat launching, or discussing the launch of, a series of satellites to help track transoceanic flights anywhere in the World, that could also be useful to determine vertical separation.

Quite a few months have passed and I seem to have lost track of this. So I am here to ask those who know more about it: 

what are the recent developments in the satellite-based tracking of aircraft?
The German Space Agency (DLR) worked with ESA to track flights from space using ADS-B, the same technology behind flightaware etc.
Some info about it is here

A commercial entity, called Aireon, is planning a global constellation to monitor aircraft that will piggy-back upon the next generation of Iridium satellites. But, unfortunately, the recent setbacks to SpaceX launch capabilities have delayed Aireon's schedule. The first launch of the Iridium-NEXT satellites occurred on Jan 14th 2017 and the entire constellation - providing near global ADS-B coverage - is planned to be complete by mid-2018.

Aside from ADS-B, there is also research going on to track aircraft through their exhaust emissions (something I'm working on right now). Nothing is published about that yet, though.