In 2006 Element Skateboards developed something called featherlight helium board construction. It allowed for boards to be 10% lighter than their current boards which were already developed to be lightweight. Each board has 5 air chambers built into it, which decreases the weight, but also increases the strength at the same time. You can see these chambers here:
Now 2008 comes along, and Element took the same featherlight helium technology, and mixed in a little carbon fiber. They added carbon fiber to the top veneer, and they now call it push construction. Element claims that because of the carbon fiber strength to weight ratio, the board is extremely lightweight, but also almost impossible to break.
The positive negative series are available in 3 different board styles. The top screen is the same on all boards, and looks like this:
Then there are the following designs; Darrel, Muska, and Tave.
I found a couple of these on Amazon, which you can see here. At the time of writing, they were selling for around $90, much less than the $199 MSRP that I had read about.
I also found a couple videos featuring the new push construction: