I'd heard something about this stuff a while back but hadn't had the opportunity to read/see anything on it. Thanks for posting this.
They say that since it's "heat-activated" that material like metal armor plating won't cause it to expand but that the heat of a human body will. I wonder though, what would happen if you shot a vehicle that had been out in the sun all day (like in the desert in Iraq). It seems to me that the heat absorbed by the metal might be enough to activate the bullet thereby keeping from penetrating. I don't know, I'm just curious.
If it works as well as they say it does, it sounds like some pretty cool stuff.