I recall seeing a large-scale (half-metre tall) one of these at Uni Adelaide's Open Day a few years ago - I had to explain to the public what it was, so I got the quick rundown from the guy who built it. The physics of it is really quite simple - put a speaker pointing down the length of a sealed cylinder with some sort of gas, then drive a standing wave. You get nodes at well-defined places where the sound waves cancel, and thus the pressure is higher (or lower, can't be bothered working it out right now) and thus the temperature is higher (or lower). Compress a gas and you heat it up - pump up a bike tire and you'll know - the opposite happens for low pressure.
You then have a tube with n hot spots and n cold spots. Tune it right and you can have just 1 hot spot and 1 cold spot (plus the end with the speaker of course) - used correctly, this can be made into a heat sink. The main problems (IIRC) were that the sink was only so big, so you couldn't exactly put it on the back of a fridge and expect much; and that you still had to remove heat from the hot end. Clearly these guys have solved the former by making lots of little ones, but without reading more I'm not sure how they're dissipating the heat. Come to think of it, I'm not sure how they're fitting much gas inside a CNT as it is... Perhaps it's a completely different principle. Dang.
Still, nice find.
