They only do it for some games, and you need to get wrist bands for each kid and line up by a door that leads to right field at the end of the game. They only give out about 1000 wristbands. The wait in line took a while but once they start letting people through it goes REALLY quickly. The ushers herd you through, and you go through the outfield towards first base. The kids start running at first base and then go around to second, third and home. Parents can go with younger kids so my husband went with Little Man, the other two went on their own.
Unfortunately I didn't get a single picture of anyone because the ushers really rush everyone through. As the kids are running, the parents are sent back into the stands and then back down towards home plate to pick up their kids. I understand that they want to get people out of the park so that they can clean up but it would have been better if they would let us have some more time to.
The kids still had fun doing it, and I would encourage other baseball fans to do it. Just don't expect to get to take a leisurely stroll around the bases or get any cool shots of your kids coming home (unless maybe you have a relative stay in the stands and wait for the photo op. If we do it again, that's what I would probably do.