Einstein's theories show that nothing can travel faster than light. However, just very recent results from CERN, the large Hadron Collider in Europe, show that Neutrinos they sent through the ground from Cern toward the Gran Sasso laboratory 732km (454 miles) away in Italy. They have re-checked their methods and their calculations to ensure that the results are correct and they are sending their results to other science agencies to independently verify their findings. This could well be one of the biggest discoveries in Science because its implications are enormous.
How? Well for many reasons. One example is that the idea of time travel (not merely changing speeds of time between different reference points) is currently deemed not possible because of the idea that nothing can go faster than the speed of light.
Also, by finding out why this could be, scientists might be able to discover more things we did not know about.
Update: 23 Oct 2011
Ronald van Elburg of the University of Groningen in the Netherlands posted in a paper posted to the physics pre-print website arXiv.org, argues that the Italian scientists failed to account for the fact that the GPS satellite they used as their timekeeping device is moving.