Well not entirely true anymore. Recent studies show that it is possible to make light travel faster through cesium gas than pure vacuum. Apperantly when a pulse of light what fired through cesium gas it actually exited the chamber before it had finished entering it (not quite travelling back in time as some theories would suggest).
Keep in mind that accurate scientific reporting is rarely to be found in the major news channels. A better synopsis and interpretation of the experimental results can probably be obtained from the scientists themselves.
Some relevant quotes:
Since a Buick has nonzero rest mass, Cecil was correct in telling his readers that it cannot exceed the speed of light.
An analogy for these types of experiments: Suppose I’m walking through a doorway, travelling at the Speed of Chronos. I walk with my arms out in front of me. Now, unless the doorway is exceptionally thick, my hands are going to leave the doorway before my body enters it. Does this mean that I’m travelling at faster than the Speed of Chronos, or that I’m going back in time? No, of course not.
The situation is analogous with almost all of the claimed “light faster than light” experiments. They’re using a light pulse of some length, and measuring different parts of the pulse. They’re counting the pulse as having gone into the material when the middle of the pulse goes in, but counting it as leaving when the leading edge of the pulse leaves. Put it that way, and you realize just how boring these experiments really are.