Article in the Wall St. Journal today: "Air War: Winglet Verses Sharklet". The wingtip attachment called "blended winglets" is patented by a small Seattle company by the name of Aviation Partners, Inc. They own a 55% share of a joint venture with Boeing to market "blended winglets" to buyers of Boeing jets. 3,500 Boeing jets (100+ airlines) are equipped with winglets.
Aviation Partners had been in discussions with Airbus for 5 years to set up a similar arrangement although Airbus was working the "sharklet" design. Airbus presented the sharklet design to Aviation Partners and they said it infringed on their patent and asked for royalty payments. Instead, Airbus has filed suit in US Federal court to invalidate Aviation Partners' patent which is 18 years old. Airbus claims they are at a competitive disadvantage if they have to pay a royalty fee.
It will be interesting to see how this plays out.