A couple of times a week, the tracker checks progress on the iteration to see how things are going.
You have an iteration plan, so now all you have to do is sit back and watch the plan unfold—right? If you said yes, hit yourself on the head three times with this book (and be glad it's a thin one).
The only thing you know about a plan is that things won't go according to it. So you have to monitor the iteration at regular intervals. You need to have someone whose job it is to track progress in an iteration. We call this person the tracker.
A couple of times a week or so the tracker needs to find out where everyone is with the iteration. We don't suggest calling a meeting for this or (heaven ...