Amazon now allows users to lend out eBooks (qualifying titles only) on a 14 day basis. Once loaned, the title cannot be accessed by the original purchaser, and only one copy can be lent at a time. The eBooks can be accessed on any Kindle application (Windows, Mac, Android, iOS, etc).
Amazon’s goal is to convert customers to the eBook format—and hopefully sell more Kindles—by giving users a limited taste of the experience. The addition of the lending feature could potentially hurt Apple’s iBookstore, so they would be wise to offer a similar option.
The problem for Apple is the lack of non-iOS iBook applications. Amazon has the benefit of allowing users to read on a desktop, so each users who is lent a book is a potential future customer. If Apple offers an iBook application on the Mac App Store, then they—and the users—could benefit from a lending option.