I have recently worked with Jae Kyoung Kim, Zack Kilpatrick, and Matt Bennett on the problem of synchronization in circadian clocks. The paper just came out in the Biophysical Journal. Suppose you take a bunch of cells that oscillate with slightly different frequencies. If you couple the cells in the right way, they will tend to synchronize, and hence oscillate with a single frequency. However, it could be that the fast oscillators pull the slower ones, and the synchronous population speeds up. Or the slower oscillators drag the faster ones down, and the populations slows down after coupling. How can we make sure that the population does neither, and oscillates at the average frequency of the uncoupled population.
Jae asked how this happens in the master circadian clock of mammals. He had a suspicion that it is due to the mechanism that drives the individual cells to oscillate. In particular, he showed that if the genetic oscillator is driven by protein sequestration, then the synchronous state will exhibit the behavior observed in experiments (cells will synchronize at the mean frequency). This will not happen if the oscillations are modeled using the more popular Hill kinetics.
Thus the synchronous oscillations of thousands of cells can provide clues about what makes each of the individual cells oscillate. Here is a nice overview of the paper.