The fastest FPS camera you've ever see probably isn't even close to this one in the MIT labs, which can shoot at a recor speed of 1,000,000,000,000 frames per second! That's right! One TRILLION FPS! The purpose of this camera is to capture light waves in slow motion. The camera is developed by the MIT Media Lab's Camera Culture group working with chemists from the school's Bawendi Lab, and doesn't really work like your DSLR:
The new technique, which we call femto-photography, consists of femtosecond laser illumination, picosecond-accurate detectors and mathematical reconstruction techniques. Our light source is a Titanium Sapphire laser that emits pulses at regular intervals every ~13 nanoseconds. These pulses illuminate the scene, and also trigger our picosecond accurate streak tube which captures the light returned from the scene. The streak camera has a reasonable field of view in horizontal direction but very narrow (roughly equivalent to one scan line) in vertical dimension.
With this gadget they can study the behavior of the light, since it can capture one frame each 1.71 picosecond! Now THIS is fast!