It is among the fastest available. As with any DSLR, when the camera's buffer fills the frame rate is controlled by how quickly you memory card can swallow data. All in all, an exceptional performance.
About this fast (composite of 7 frames): http://www.printsandpixels.com/DigitalWorks/Composites/15196672_MnhGJg#!i=1136916626&k=PfNt3jT&lb=1&s=A This is why I chose this camera. I love it! It will usually buffer about 15 shots for me with a 60 MB/s card shooting in RAW at maximum size.
If you use the manual instead of auto mode, you can shoot up to 8fps. This is a good trick to use when shooting people. There always seems to be someone who doesnt smile, blinks etc. If you tell them your going to shoot one picture and then fire off the 8fps your pretty much guaranteed to get genuine, full smiles and everyones attention. :-) It is also pretty effective at fast, short events. After the June 1st, 2011 tornado, I used the 8FPS capturing several tree's being crowned or taken down. The 8fps has allowed me to choose the most 'breathtaking' of the shots, IE, a full sized tree hitting the ground and bouncing up, a top of a tree beginning its free fall, etc. This camera has always delivered!