I have mentioned the controversial EM Drive several times in Space Propulsion related articles. We may know soon if the drive really works once and for all. Guido Fetta of Cannae Inc has announced that they will work to launch a 6U cubesat to test the drive.
Fetta has an interest in this as he is the inventor of the Cannae Drive, which is related to the EM Drive. Both are closed microwave based systems with no conventional exhaust as the propellant.
While proving the drive does work would be a huge milestone for space travel, few in the scientific community give it much home.