Apple has given the Apple Store an over-the-air update today changing the free content offer. Previously it was Color Zen, now it's a children's book “Away in My Airplane.” This will be delivered through the iBooks app.
Apple retail workers were told about the change on Monday morning and have been told to use the change to give them a reason to talk about the iBookstore and iBooks app.
These free content promotions are designed to encourage people to visit the Apple Stores more often; Tim Cook made it a goal of his to improve the 80 percent third-party market share of iPhone sales. It'll also be useful to encourage customers to buy further into the Apple eco-system through things like Macs, the iPad, and other Apple products. The iPhone is most customers' first experience with Apple and if the device is sold in third-party stores Apple can't up sell its products.
Apple has also started offering a trade-in program that will help increase iPhone upgrades in store. There's also a "Back to School" promotion that gives customers a $50 gift card.