I recently did some testing of the 7D for BIF.
The subjects were fulmars at a distance of 200M over a grey sea. Fast subjects over a similar background. The day was overcast. I was impressed with the AF and tracking capabilities of the camera. The keeper rate was probably around 75%.
I switched to the 1Diin and felt that the AF was faster for the initial pick up, but that they 7D tracked better over the sea. We are talking margins here, but 0.1 of a second is a lot. I did not time the differences and these differences could be caused by familiarity or settings that I have not investigated. The keeper rate from the 1D was probably around 60%.
I say probably because an Otter turned up and I formatted all my test cards to get as many shots as possible. Being able to switch to ISO1000+ on the 7D was a real bonus as the Otter was under a bridge, but that's for another thread.
So in summary. I felt the AF was good, and the tracking excellent under testing conditions.