theodp writes: After shelling out a reported $90MM to buy PlanetAll in 1998, Amazon.com shuttered the site in 2000, explaining that 'it seemed really superfluous to have it running beside Friends and Favorites.' But years later in a 2008 patent filing, Amazon described the acquired PlanetAll technology to the USPTO in very Facebook-like terms. And on Tuesday, the USPTO issued U.S. Patent No. 7,739,139 to Amazon for its invention, the Social Networking System, which Amazon describes thusly: 'A networked computer system provides various services for assisting users in locating, and establishing contact relationships with, other users. For example, in one embodiment, users can identify other users based on their affiliations with particular schools or other organizations. The system also provides a mechanism for a user to selectively establish contact relationships or connections with other users, and to grant permissions for such other users to view personal information of the user. The system may also include features for enabling users to identify contacts of their respective contacts. In addition, the system may automatically notify users of personal information updates made by their respective contacts.' So, should Facebook CEO Mark Zuckerberg worry about Amazon opening a can of patent whup-ass?