The technology comes from experimentation with tanks. BAE developed a way to make tanks "invisible" to IR devices. Hexagonal plates which can change temp quickly are fixed to the tank hull and copy the heat signature of it's surroundings. So when you look at this tank through IR goggles it simply looks like a bunch of trees. Or the panels can be manipulated so you see a car instead of a tank.
Now I don't expect this to be standard equipment anytime soon because (just IMO and not knowing anything else) it would be hard to juggle with other protective equipment like reactive armor, cages, etc. And technology is renowned for failing on the battlefield, like the GPS. Still, any day now I expect Crysis to come to life with frozen aliens attacking LA and whatnot .