Edited- Neutrinos, obviously. Brain fart.
I think Fermilab-MINOS can measure such things but I believe I read they have to update and recalibrate a bunch of things to get more accuracy, first. (Recall MINOS already saw this same effect but not at a statistically significant level. Obviously, they now have an incentive to improve their accuracy.)
http://www.nature.com/news/2011/110922/full/news.2011.554.html
http://arxiv.org/abs/1109.4897v1
http://usersguidetotheuniverse.com/?p=2169
http://news.ycombinator.com/item?id=3027056
Perhaps the end of the era of the light cone and beginning of the era of the neutrino cone? I'd be curious to see your probability estimates for whether this theory pans out. Or other crackpot hypotheses to explain the results.