Here's an article about a new paper in Physics Review Letters:

http://focus.aps.org/story/v13/st3

Electromagnetism may allow you to transfer momentum between an object
and the vacuum. If true, this implies a mechanism for propulsion
without propellant mass. The numbers are of too small a scale to fight
the earth's gravity, but perhaps in a weak gravitational field, it
could amount to anti-gravity?

quoting the following:
Both Leonhardt and Loudon warn that the predicted effect may be
difficult to spot. For example, Loudon says, if the material contains
a few freely moving electrical charges, they will experience larger
forces that may obscure the subtle quantum effect. Still, Leonhardt
says, "This is a smart idea."

But if the freely moving electrical charges make it difficult to
detect in the lab, could this other article be of use?
http://www.physicsweb.org/article/news/8/1/9