That's the first day of Nike availability. Always worth the couple extra week wait though (to me).
I was a bit disappointed that it wouldn't come out on the 21st but I don't mind waiting. I love my Nike series 2 so it'll be worth the wait.
I've enjoyed my Nike series watches as well but just bummed that they can never get them out the same day the others launch. Ah well, I'll at least have the phone to open next Friday and my wallet can wait an extra couple of weeks for the watch to arrive.