Having played the original Borderlands, I never thought of Pandora as a Jungle. It really seemed more like a perpetually stretching rocky desert. The Pandora of Borderlands 2, however, is a much more diverse place: There are more environments, more monsters, and a LOT more guns.
Anyways, the trailer is called "Wimoweh", so I think you have an idea of where I'm going with this. Borderlands 2 wakes the lion up on September 18th.