Just received an email from AA:
Hello grrizzli,
You can now follow your checked bags from check-in to carousel with your smartphone, laptop or tablet. See real-time information about your bag's status, including when your bag is checked in, on a plane or at baggage claim. All you need is your bag tag number or your record locator.
And, if your flight has Wi-Fi onboard, you can track your bags in the air for free. Here's how to get started:
Go to aa.com/baggage
Click "Track your bags"
Enter your last name and bag tag # or record locator
Seems like a very good feature.