A very interesting review in APS's Physics today on another paper that tries to measure any violation of a local Lorentz symmetry (the link also gives you a free copy of the PRD paper).
What makes this paper "interesting" is the list of authors. One of the author is a "Steven Chu". You may have heard of him! :)
I'm sure our current Secretary of the Dept. of Energy did this work before he was appointed. In fact, there was a similar preprint related to this work that he co-authored that appeared on arXiv the day that Chu was confirmed at the Energy Secretary. It is nice to know that he was an active physicist right to the point that he was appointed to this position.