The goal is to make the object less noticeable at a glance, because unlike a soldier, an air conditioner can't adjust its position and hunker low to the ground, or slip behind a tree to help further disguise itself. In other words, it may not be a perfect invisibility cloak just yet, but as a way to improve aesthetics, there's a good chance Voldemort won't notice that hideous breaker box on the wall. [MIT News]