The Overdrive.com system is compatible with PC, Mac, iPods and iPads, Sony readers, the Nook reader and any reader that supports e-pub format. The Kindle will be available soon on this service as well.
The way Overdrive.com works, the school would subscribe to the service every year. A portion of the subscription goes towards the purchase of e-pub content. Of course additional content can be purchased anytime. Patrons then go to the website, enter a student ID or library ID and then browse the books in the school's online library. Once a book or books are located they add the books to their cart and then check out. During the check out the system will download the books to the device. The books remain active for 2 weeks then expire automatically on the device and are then available once again for check out. If a book is not yet available the patron can place the book on a wait list. I imagine there is some sort of email notification when the book is available.
I am not 100% familiar with the way the system works but there is an excellent video showing how it all works. See the video here
Here is a link to the Park Falls Overdrive.com web site. I downloaded the Overdrive APP to my iPod, all I need now is a library card from them and I would be able to sart to check out books!!