GGP is correct that you could describe the motion of the planets (and sun) in terms of complicated orbits about the earth. However, as others have pointed out in the thread, there is a preferred (inertial) frame -- that of the fixed stars (cf. the Mach principle). The sun moves with respect to that frame, carrying the solar system with it. So the frame of the sun (or, more correctly, that of the center of mass of the solar system, which happens to pretty much be the sun) is objectively closer to being inertial than that of the earth. So to suggest that the reasons for favoring the sun as the origin of the system are purely technical (as opposed to physical) is perhaps a little disingenuous.

Actually, its even possible for the group velocity to exceed the speed of light, without violating relativity/causality. See for e.g. http://arxiv.org/abs/physics/0101068

This is really wrong. Temperature has a precise mathematical definition (relation between system energy and entropy), which is universal. Applied to most systems, this yields the concept of temperature familiar from everyday life. Indeed, some systems are such that they can be manipulated to a state of `negative temperature', in the formal mathematical sense. However it is definitely not the case that the concept of absolute zero is tied to the motion of atoms in particular, or that it is merely 'a reference point' that has later been surpassed.

(I kinda hope you're just trolling, otherwise please just STFU when you don't know WTF you're talking about. )

Not really... negative temperature can be a 'meaningful' concept in some scenarios, but it's not necessary to invoke it here. Temperature is a property of an object such that two objects in contact (or exchanging radiation, etc) with different temperatures will exchange energy (heat) so as to try and 'meet each other in the middle', i.e., hot one loses energy to the colder one until the the temperatures become equal. Basically the character of laser beams is that they are not-very-thermal-at-all, so you can think of the incident beam as having some temperature very close to absolute zero, much less than the particles they're being shone on. Statistically speaking, the temperature of the particles will lower towards that of the incident laser beam, and the scattered laser photons will be 'heated', and carry away some of the original thermal energy of the cooled particles.

No, it shows that bloggers and reporters (and slashdot editors) need to sensationalize preliminary results or possible explanations to get readers.

Of course they need to sensationalize. Otherwise these reports are just, well, preprints! And preprints that aren't in your field probably won't be of interest to you.

The arXiv blog is cool, and it's nice to see some interesting preprints from outside my field pointed out, but I only take this to mean that this could possibly be a bit more interesting to me than the other ten-thousand-odd astro-ph preprints I won't be reading this year.