For the test run, a thin layer of the material was painted on dummy missiles, and radar waves aimed at them had a difficult time registering them.
The paint particles don't make the missile's detection on the radar disappear completely, but make it exceedingly difficult to positively identify the object as a missile. In the future, this development will allow any missile or jet significantly decreased radar detection.
Even though they may not entirely disappear from radar screens, this technology is a considerably more cost-effective method to evade radar detection than purchasing an American stealth plane for $5 billion.
Link via Popular Science | Photo (unrelated) by Flickr user eschipul used under Creative Commons license
If I were looking to use this paint I would want to see a test with a plane. Missles already have a small radar cross section as they have fewer flat reflective surfaces.