After over a decade of skepticism, a newly released NASA paper seems to show that it works. They don't say why it works, and it only works a little bit, but even if it's only a little bit, then it breaks some accepted laws of physics, and opens some doors to future long range and duration space propulsion systems.
Link:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140006052.pdf
