Well, the heated air can be ducted out and away from the system, and the pressure can be controlled so you don't get too cold... all of their vortex tubes come with control valves I think.
Imagine a computer controlled control valve so that when the temp goes up, so does the pressure to balance it out... *drool*.
Woohoo, 14th person to solve the 4D rubik's cube...ever! http://www.superliminal.com/cube/cube.htm
Watch me solve a regular cube in 24.2 seconds at www.rubiks.dk videolist, Daniel Hayes!