Mountain View-based Friendster said today that it has snagged a fourth patent, U.S. Patent No. 7,451,161, around compatibility scoring of users in its network. According to the firm, the patent covers method used to calculate compatibility between users of its social network. According to the firm's U.S. Patent and Trademark filing, the patent was actually granted last month, on November 11th. Inventors on the patent are Xiao ming Zhu and Christpher Lunt, and the application has been in process since April 28 of 2005. Friendster was represented by Patterson & Sheridan, LLP in the patent application.