Negative Temperature

I'm not entirely sure how to feel about this one.  You see, in a recent issue of Science magazine, a group of physicists have claimed to have achieved negative temperatures.  That is to say, a temperature of below absolute zero.

I'll back up a step and review, so you can understand why I can't help but approach this idea with some trepidation.  You see, temperature is basically a measurement of the amount of energy in a system.  At the level of particles, that basically translates to movement-- both positional and vibrational.  The lower the temperature, the less energy in the system, and the less movement.  At absolute zero-- about 273 degrees below zero centigrade-- there is no more movement.  That's why it's absolute-- you can't have less than no movement.  So how could these scientists have achieved such a feat?

As far as I can tell, by redefining "temperature."  Although what I gave is the simple, basic definition of temperature, at some point physicists decided that it would be more useful to refine this definition in a variety of ways.  In particular, in terms of the average energy of the system rather than the specific energy at any given instance.  For the most part, this doesn't make any difference-- the average energy still can't go below zero.

However, with enough control over the particles, you can create a situation where instead of having a normal distribution of particles (that is, a bunch of particles moving at close to the average and a few zipping around as outliers), you can flip that, creating a situation where almost all of the particles become "outliers", being held artificially in extreme states.  This allows you to create a pattern of behavior for the particles that is opposite to how they behave at "positive" temperature.  And if it's opposite to the positive temperature, why, then it must be negative temperature, right?  Right?

I'm not denying that it's an impressive achievement, but I really feel like there's an aspect of... semantics?  Philosophy, perhaps?  Lurking in the shadows.  On the one hand, if you can look at a system and say, "Potassium atoms in a particular arrangement at positive temperature behave in a certain way.  At zero temperature, they have these other characteristics.  In this new third situation, they have a set of characteristics that are not described by either previous category, and that in fact look completely backwards from the atoms at positive temperature, so it makes sense to call it negative temperature."  Classic "If it looks like a duck" territory.  On the other hand, the fact that your highly technical definition makes it possible to achieve a situation that was previously considered a theoretical impossibility makes me wonder if, just perhaps... you need to rethink your definition instead.