The trick, they report in a paper to be published in Physical Review Letters, is to embed a matching "antiobject"--the metamaterial equivalent of a voodoo doll--in the outer layer of the post. The scattering from the embedded antiobject exactly cancels the scattering from the object, Chan says, "so it looks as if there is nothing there." Because the hidden object remains outside the post or umbrella, it can detect light from its surroundings.
The scheme does have limitations, Pendry notes. The umbrella works for only a single frequency, has to be specifically tailored to the object to be hidden, and won't completely hide something that absorbs light. Still, Pendry says, "that's carping on my part--it's really a neat idea."
The application for left-handed materials is very vast. I just wish that we don't attach it to such popularization and suffer from the same misunderstanding as the "teleportation" phenomenon.