It has an app that adds functionality to the device to modify temperature controls, such as raising/lowering the temperature, and increasing the temperature as you draw, but lowering it when you're not drawing to conserve battery.
It's a great app that adds a fair amount of value to the product. It sucks to know that this won't be getting updated, or if I buy a new iPhone, I won't be able to install without jailbreaking.
I would love for Plume (creator of the Pax) to open source the app so that some users are able to build and run it, and the community would likely add some improvements. But we'll see what happens I suppose.