Back here in November, I covered the story of an American tank that was destroyed in Iraq by a previously unknown weapon. Wild speculation reached for suggestions as wild as a second world war anti-tank rifle given depleted uranium rounds or an electromagnetic railgun, but it now seems that it was almost certainly an RPG7 using a new type of round, called a PG-7VR. This evil contrivance defeats the reactive armour on a tank (which explodes back around a hit to disperse the molten metal that actually penetrates the armour) by using effectively two warheads - one blows off the reactive armour and the second kills the tank.
Worryingly, the reason why these have been found to explain the mystery is that they have become much more common in Iraq.
This also puts another light on this...
Background here and here