The basic idea of using high frequencies across a wide spectrum as well penetrating radar of a sort has been known for quite awhile, even if the "simple matter of an implementation" may have lagged behind. The FCC was really worried about this becoming possible over approved UWB (Ultra WideBand) frequencies... thus, they put really serious power level limitations on UWB radios approved so far. Not that strictly nefarious use of such technology necessarily follows FCC guidelines anyway. But if nothing else, it's an effective means of ensuring that the "see through your apartment walls" device doesn't show up in SkyMall anytime soon.