Revolution in Resale of Digital Books and Music - NYTimes.com

A different conceptual model for digital goods

"Sales of digital material are considered licenses, which give consumers little or no ability to lend the item. The worry is that without such constraints digital goods could be infinitely reproduced while still in the possession of the original owner.
Both the Amazon and Apple systems aim to solve this problem. Amazon’s patent envisions a book or movie or song being kept in a customer’s personalized “data store.” When an item is no longer wanted, the user could sell or trade it to another user, an action that would automatically delete the item from the first user’s store."

Revolution in Resale of Digital Books and Music - NYTimes.com