By John Letzing Of DOW JONES NEWSWIRES SAN FRANCISCO -(Dow Jones)- Yahoo Inc. (YHOO) has told Facebook Inc. it has 16 patents in addition to those it has already filed litigation over that the social site may be infringing. Facebook disclosed in a regulatory filing Thursday that Yahoo sent a letter late last month informing the Menlo Park, Calif., social-networking company that "they believe 16 patents they claim to hold 'may be relevant' to open source technology they allege is being used in our data centers and servers." Facebook said Yahoo hasn't threatened a lawsuit over the matter, but added that "it may do so in the future." Yahoo sued Facebook in March for allegedly infringing 10 of its patents related to online social services, advertising and privacy features. Yahoo later asserted two additional patents in the case. The lawsuit has drawn criticism, as Yahoo historically has used its patents more for defensive purposes rather than suing its peers. Yahoo hired Scott Thompson as its new chief executive in January. Thompson has expressed a desire for the Sunnyvale, Calif., company, which is in the midst of a turnaround effort, to start pursuing new revenue streams. Facebook has countersued Yahoo, asserting its own 10 patents. Facebook, which Thursday filed additional papers for an IPO that could raise as much as $13.6 billion, now has two large, fully owned and operated data centers in operation in Oregon and North Carolina. The company has paid a great deal of attention to developing its own server computers to power those data centers. Facebook recently acquired hundreds of patents from International Business Machines Corp. (IBM), many of which are related to data center operations. Spokesmen from Facebook and Yahoo didn't respond to requests for comment. -By John Letzing, Dow Jones Newswires; 415-765-8230; john.letzing@dowjones.com
