It is somewhat striking to see a list of several PubMed articles with roughly 600 co-authors under each of them. ScienceRoll suspected that the first author (Aubert B.) must have a lot of friends and asked for an explanation. Here it is.
The last name in the author list is "BABAR Collaboration." A Google search shows that "BABAR is a High Energy Physics experiment located at the Stanford Linear Accelerator Center, near Stanford University, in California. The goal of the experiment is to study the violation of charge and parity (CP) symmetry in the decays of B mesons." According to Wikipedia, a meson is a strongly interacting boson, that is, it is a hadron with integral spin. I hope this makes it clearer :)
The BABAR Collaboration consists of approximately 600 physicists and engineers from 75 institutions in 10 countries. This can probably explain the 600 co-authors.
Related reading:
BaBar experiment from Wikipedia, the free encyclopedia.
500 authors of Grand Rounds
The "BIG 1-98" randomised clinical trial really is big: 885 authors are listed on this Lancet article http://goo.gl/lKEfw via @JRBtrip