Well, maybe not quite faster than a speeding bullet - but still pretty damn fast. A cat's tongue can complete four full laps of milk or water - every second. That comes to - roughly one meter or three feet per second. That's a lot faster than the human eye can see, much less what the human tongue can do.
The New York Times website explains how four scientists from MIT, Virgina Tech and Princeton had to combine disciplines to discover just how a cat does it, why a cat has to do it (unlike humans, they can't fully close their mouths to create the vacuum needed to produce suction), what the always essential to liquid mechanics Froude number has to do with it, how African safari YouTube videos helped validate their hypothesis (and elegant mathematical formula) that correlates a cat's lapping speed with the size of the species of the cat and - most critically of all - why cats are more elegant than dogs when lapping up water.
UPDATE - Los Angeles Times also has same story, courtesy of Nature Magazine: