On the surface, nothing. Yet, dig a little below the surface and it's interesting where Yahoo! fits in to these discussions.One of the most intriguing aspects of new CEO Marissa Mayer's first conference call at Yahoo back in October was her mention that Yahoo was in the unique position to be a partner to a great number of players in the mobile/web space. And she's right. Yahoo! already provides key data to every Apple (AAPL) iPhone. It uses Microsoft's Bing search engine to power its own searches. It used to use Google's (GOOG) search engine and ran to Google after Microsoft made a hostile bid for the company in 2008. And Yahoo! was an early partner of Facebook's Connect program. Now that Marissa Mayer's come in to Yahoo!, she has squarely refocused the company on mobile. They have revamped key mobile properties like Flickr as well as stalwart Web platforms that deliver important traffic like Mail and Homepage. The fact that Yahoo! has built great Web services in the past makes them an interesting partner for Apple, which has been rightly criticized for being too slow in Web services in the last year. Yahoo has great traffic and great relationships with existing brands. They are the No. 3 Web site in the world, behind Google and then Facebook. They've also killed the patent war with Facebook a few months ago. So all this makes them an intriguing potential partner with Facebook. The search partnership between Microsoft and Yahoo hasn't led to the kind of results that Yahoo! had been hoping for when Carol Bartz signed it in 2009. Yahoo! might seek to end the partnership with Microsoft in March. If they do, they could conceivably turn to Google as a potential partner who could monetize Yahoo!'s traffic much more lucratively than Microsoft can.