Walker Digital [NPE] filed suit against Facebook, Yellowpages.com (AT&T), and Goldstar Events over four patents related to offering discounted deals online. 5/17, District of Delaware, 1:2011cv00434.  Walker Digital has used the same set of patents in two prior suits against 10 other defendants, including Google and Amazon. Walker Digital has filed a total of 27 patent suits in 2011 to date.  This is one of two suits filed by Walker Digital against Facebook on May 17, 2011.  Since November 2010, Walker Digital has named Facebook as a defendant in six separate suits.