A new patent dispute is brewing in Silicon Valley as Yahoo seeks to impose a licensing fee over Facebook using 10-20 of their patents in advertising, the personalization of Web sites, social networking and messaging.

When asked by New York Times’ DealBook, Yahoo! replied in an e-mail stating that, “Yahoo has a responsibility to its shareholders, employees and other stakeholders to protect its intellectual property.  We must insist that Facebook either enter into a licensing agreement or we will be compelled to move forward unilaterally to protect our rights.”

While Facebook spokesman Barry Schnitt stated that they have yet to review Yahoo’s claims, since Yahoo contacted them and the NYT almost at the same time.

Nothing has been said as to whether the two companies have discussed the patent infringement claims and how much Yahoo is asking for licensing fees.

Back in the early 2000s, Yahoo dealt with patent issues with Google, which they settled when they acquired Overture Services and received 2.7 million shares from the search giant before Google went public.  And since Facebook is in the final stages of going public, Yahoo might want a piece of the Facebook action as well.  Facebook going public puts them at a $100 billion valuation.

But some sources say that Facebook’s IPO has nothing to do with Yahoo!’s patent claims as new CEO Scott Thompson only wants “to boost the performance of all aspects of the company’s business.”

Yahoo has 5,931 patents while Facebook only has 226 patents, so there is a possibility that Facebook infringed some 10-20 Yahoo patents.  We’ll just have to wait and see how this one plays out.