Modified invisibility cloak could make the ultimate illusion

An illusion device that makes one object look like another could one day be used to camouflage military planes or create "holes" in solid walls.
The idea builds on the optical properties of so-called metamaterials, which can bend light in almost any direction. In 2006, researchers used this idea to create an "invisibility cloak" that bent microwaves around a central cavity, like water flowing around a stone. Any object in this cavity is effectively invisible.
Now a group of researchers has gone a step further. "Invisibility is just an illusion of free space, of air," says Che Ting Chan, a physicist at the Hong Kong University of Science and Technology and a co-author of the study. "We are extending that concept. We can make it look like not just air but anything we want."

Full story by Lisa Grossman on New Scientist