As far as I'm concerned, the Canon 1D Mk III is world's best camera for sports and action. Why? Easy: It runs at 10 frames per second, critical for anything that's moving faster than you can see, and it works great at ISO 6,400. ISO 6,400 is two stops faster than ISO 1,600, so an f/2.8 lens becomes twice is as fast as an f/1.4 lens at ISO 1,600.
ISO 6,400 is insanely useful. For those of you who remember film, ISO 1,600 was about tops for color and it was very grainy and dull. Konica 3,200 sucked. There was no retail ISO 6,400 film, period. The fact that the 1D Mk III makes any images at all at ISO 6,400 is laudable; the fact that they look great is insane. Read the very informative review here