watch any start of an elite mile race on Youtube.com and you'll notice that the runners cover the first 9 meters (mile start, to the 1600 start) in 2.1-2.3 seconds.
http://www.youtube.com/watch?v=NF4_V6bOkk4&mode=related&search=
http://www.youtube.com/watch?v=2iWzUXiaA5Q
I found this very interesting, because I always assumed it would be closer to 1 second (1.3-1.5 to be more precise).
If a relay runner splits a 4 flat they are averaging approximately covering 9 meters in 1.35 seconds (15s per 100m).
having a "rolling start" in a baton exchange is close to being a full second faster than your regular waterfall standing start (not including all the pushing and pulling as runners try to get off the line).
I know that there are many other variables that dictate times, but I thought some might find this fairly unimportant research I did interesting.