I wanted to go through and explain how this experiment worked in a simple way, but it ended up taking me a long time, and I had to contact old physics professors and it started to feel like a research paper, and I wasn't going to get a grade on it so I just decided to say it with simple metaphors.
http://arxiv.org/pdf/1105.4714v1.pdf
Basically, a mirror is fashioned in such a way that it will reflect/block quantum particles. These are easy to make; as far as I know it's just a perfectly flat sheet of metal, but anyway.
It's already been known that if you take two such mirrors and place them together, that they will sort of stick to each other. In quantum physics, this led to/supported the theory that the universe is filled intangible, immeasurable, "virtual" particles, that only exist in as far as they are able to effect other particles as real particles do, yet they do not themselves really exist.
This experiment took the one mirror, and vibrated it very quickly (5% the speed of light) and miraculously photons began to spill off the surface of the mirror.
This is explained by the sea of virtual particles. The mirror is thought to move so fast, that the particles are left with a vacuum. In their haste to balance themselves, they move into the real world for a bit, and in the transfer, release some energy in the form of light.
True enough, the law conservation of energy really isn't broken, but that's only if you accept quantum mechanics. Something some people do not do, because it's riddled with ugly paradoxes.