Yahoo! has accused Facebook of infringing on ten of its patents in a California Federal Court. The patents in question have been described as covering features of social networking such as customised content feeds and spam detection as well as online advertising.

The action has come at a sensitive time for Facebook as it prepares for a highly anticipated IPO in the coming months. Yahoo! previously sued Google in 2004 for patent infringement. In that case, Google was given license to Yahoo! patents in exchange for shares in the search engine giant days before it went public.

Facebook has responded to Yahoo’s lawsuit by filing an infringement counterclaim on ten of its own patents relating to, amongst others, news feed and photo tagging functionality. The social network will be hoping to use these patents to negotiate its way to a settlement. Facebook’s relatively weak patent portfolio has been bolstered in recent weeks by its purchase of 750 technology patents from IBM.  A strong patent ‘war chest’ is seen as essential for software companies today as intellectual property becomes an increasingly litigious area.

Patent disputes have dominated the headlines in the technology sector for months. Until recently however, the most high profile litigants have been smartphone manufacturers and authors of mobile operating systems (see previous article here). This latest action could see social networks entering the patent battlefield and the progress of the case will be keenly observed by nervous CEOs in Silicon Valley and Dublin’s Silicon Dock alike.

Contributed by John Magee.