http://www.bbc.co.uk/news/science-environment-17364682
I am sure we all remember the experiment announced in September which suggested that neutrinos could move faster than the speed of light which disproved Einstein's Theory of Relativity. This announcement was controversial, being met with excitement and skepticism. The article linked above is about a repeat test of the speed of the subatomic particles. This test was ran at the same laboratory, but by a different group, and the neutrinos were found to not travel faster than light, instead being clocked at precisely the speed of light within a small range of error. This new experiment offered relief to the physics community, ensuring them that a century of physics and relativity were not wrong. Further experiments that will finally put an end to speculation about neutrino speeds will take place at the end of the month.
However, I wonder what it would be like if the original test data was correct. Physics, especially relativity which holds the speed of light to be the Universe's absolute speed limit, would have to be reworked and rewrote. This would have changed much of what we believed to be true.