What do Twitter co-founders Jack Dorsey and Christopher "Biz" Stone have in common with Thomas Edison? That's easy, they're all patent holders. Issued today, the USPTO's database details a messaging system where users can follow each other and display messages without a unique recipient. Last time we checked, this is how Twitter works. Officially assigned to the social network, the application was filed in July 2008, listing Dorsey and Stone as the intellectual property's inventors. Now for those of you thinking that Twitter is gearing up to slap other companies silly with mountains of infringement lawsuits, think again. Around this time last year the company announced its Innovators Patent Agreement, which detailed a contract between the social network and its employees saying that any of their work related patents will be used for defensive purposes only. While this not so angry bird doesn't seem too eager to attack, it might be a good idea for other companies (especially social networks) using similar technologies to assess their current setup just to be on the safe side.