Amazon Technologies Inc. was granted patent number 7,174,054 by the USPTO. Submitted back in December 2003, the patent covers a technique for allowing users "to request access to one or more electronic images of pages in a physical text." The patent clearly covers the Amazon Upgrade program via which customers can purchase access to electronic copies of physical books. Google Book Search, watch out. The difference between Google's implementation is that the Amazon system is "based on user ownership of the physical text," in other words, purchasing the book through Amazon. Unlike Amazon, however, Google is interested in providing consumers with the option to pay a fee for only the electronic copy. Amazon notes in its filing: "Existing systems have not provided users with the ability to access electronic images of a physical text in a centralized resource based on the users' ownership of the physical text."
News source: Ars Technica