http://www.physorg.com/news12084.html
Although they have become staples of science fiction, tachyons, worm holes and warp drives remain speculation, and many physicists dismiss their significance. There is, however, at least one real-world example of superluminal (i.e., faster-than-light) travel. It occurs when light passes through water.
In this dense medium, Schneider explained, light is slowed to three-fourths of its speed in a vacuum. In a nuclear reactor, charged particles flying off the radioactive rods through the water they are submerged in exceed this reduced speed.
Because these particles contain an electric charge, they emit energy, called Cherenkov radiation. Any particles they bump into become radioactive, giving the water a characteristic blue glow.
"It's not at all exotic," Schneider said. "Every time you look at the water in a nuclear reactor, the bluish glow you see is radiation produced by charged particles moving faster than the speed of light in the water."
There is also a simple cheating observation that one can mistake for superluminal velocity, basically: from the earth, wave a powerful laser back and forth across the sky. If it hits a surface and is reflected (say, on the moon), it will appear to an observer that a laser dot is "travelling" faster than light (about perpendicular to the direction you aim it).
Of course there is no single "laser dot", but rather a series of them spread out...