According to this news article, scientists have demonstrated that a photon cannot travel faster than the speed of light. Since a photon is well, a single particle of light (according to my understanding of quantum physics, light is both a particle and a wave; it depends on what properties you're trying to measure), this doesn't seem like a surprising conclusion. Apparently scientists at one point saw something that they thought was evidence of superluminal pulses, but it turned out to be just a visual effect. So Einstein has been proven correct once again.
I haven't seen the original scientific article; even if I had, I probably wouldn't follow it very well since this isn't my field of expertise. However, I think it's stretching the point to claim that this article proves time travel is really impossible. (I personally think the writer or editor made this claim to get people's attention; I guess it worked.) I'm not sure of the implications of this experiment for tachyons. Also, I don't think this articles proves that time travel via wormhole is impossible. I know there are other proposed methods for scientifically plausible time travel, but I'm not as familiar with them.
What are your feelings about time travel? Do you think it'll ever be possible? Even if you think time travel is forbidden by science or just too difficult for us to achieve, do you think it's still worthwhile using it in science fiction?