The topic has been proposed periodically in the past (http://spectrum.ieee.org/aerospace/aviation/beyond-the-black...). There are already systems in the market.

What is perhaps more boggling is that you just need a last seen GPS coordinate or set to help find the boxes and the plane - a GPS packet if you might call it. Similar emergency transmitters are already available for yachts and boats.

The mystery of MH370 may uncover a number of simultaneous problems or deficiencies of procedure.