Velocity calculation is a lie (sort of)!

Can we make velocity calculate based on when stories are *delivered* not when they're accepted? Specifically, I propose that points are counted for the iteration in which they are delivered (when not rejected), but are only allocated once they're accepted.

I observe my current iteration is often wrong about my predicted velocity because stories delivered late in the week are accepted Mon or Tues. I can make iterations start on Wed, but that also has problems and results in poor prediction.

To preempt the argument that I'm using Tracker wrong, let me suggest a) the user is never wrong and b) this "wrong" behavior is more common to than "correct" behavior on the majority of teams, degrading the predictive abilities of tracker most of the time.