The promotion runs from June 16 through September 20. International Apple Stores are also taking part in the promotion, offering users gift cards in local currency (75 Euros, £65, etc.).
Apple does a back-to-school promotion every year, usually giving students a free iPod (or in recent years, an iPod touch) after mail-in-rebate, with the purchase of a new Mac.
College students, students accepted to college, their parents and faculty and staff members at any grade level qualify for the promotion. Apple also offers educational discounts ranging from $50 to $200 off the retail price on Mac products. The promotion is good at Apple Stores, the Apple Online Store for Education and authorized Apple campus stores. A full list of terms and conditions can be found at this page [PDF].
Apple isn't the only company with a back-to-school promotion. Microsoft is giving college students a free Xbox 360 with the purchase of a Windows PC priced $699 or higher.