The TDP of the processor in the current Mac mini is 35 W (which is what makes the mini different from most desktop systems, whose processors usually have TDPs in the 65 W to 95 W range) whereas the TDP of the (Ivy Bridge) processor in this thing is 17 W, which I am guessing is what makes it possible to shrink the size so much relative to the Mac mini.
The mac mini is also available with a quad core i7 and a hard drive. Cooling is already designed into the mac mini enclosure, which the article mentions has not been finalized in the version shown. I don't see this as much of an accomplishment.
Came here to post that. The fact that Intel's version, years later, sports half the TDP and half the size isn't an innovation, it's just an optimization. As much as I hate Apple hardware I must again admit they did a thing there worth considering. No idea why you got the downvotes.