Everyone has seen a prism bend light. Now researchers have constructed a material that bends visible light in the opposite way. The odd effect, known as negative refraction, is similar to what is needed in far-out proposals for creating a cloak of invisibility. For now, however, the device only works in two dimensions, so construction of invisible spaceships will have to wait.
http://www.sciam.com/article.cfm?chanID=sa003&articleID=7BBE5A38-E7F2-99DF-31D7FBB0032C411C