Surprise, surprise, Facebook has decided to sling a lawsuit Yahoo's way after the latter first filed a patent infringement action against Zuckerberg's crew a few weeks ago. According to Florian Mueller over at FOSSPatents, the social network's alleging some IP infringement of its own -- alleging that Yahoo has run afoul of 10 of its patents. We haven't seen the complaint filed by Facebook just yet, but we'll let you know more after we get a gander at it for ourselves. Stay tuned.