One of the oldest saws in science fiction is the hyper drive, an engine that can by pass Einstein's ultimate speed limit -- the Speed of Light. Thursday's news.scotsman.com has an article, Welcome to Mars express: only a three hour trip, reporting on a New Scientist article, which claims that NASA is investigating the possibility of just such engine.
From the article, NASA has contacted Prof Hauser, "a physicist at the Applied Sciences University in Salzgitter, Germany, and a former chief of aerodynamics at the European Space Agency" who has written papers about Heim's thoeries, and invited him to a preliminary meeting discussing the possibility of building some sort of prototype to test the engine. I assume the reporter exagerates this somewhat, since it is implied that a working Z Machine powered hyper drive is as little as five years off.
The theoretical engine works by creating an intense magnetic field that, according to ideas first developed by the late scientist Burkhard Heim in the 1950s, would produce a gravitational field and result in thrust for a spacecraft.
Also, if a large enough magnetic field was created, the craft would slip into a different dimension, where the speed of light is faster, allowing incredible speeds to be reached. Switching off the magnetic field would result in the engine reappearing in our current dimension.
The US air force has expressed an interest in the idea and scientists working for the American Department of Energy - which has a device known as the Z Machine that could generate the kind of magnetic fields required to drive the engine - say they may carry out a test if the theory withstands further scrutiny.(link added to article)