The update includes improvements in two core areas. First, Yahoo will now have increased flexibility to enhance the search experience on any platform, since the partnership is non-exclusive for both desktop and mobile. Yahoo will continue to serve Bing ads and search results for a majority of its desktop search traffic.
Second, the update increases agility and sales focus. Microsoft will become the exclusive salesforce for ads delivered by Microsoft’s Bing Ads platform, while Yahoo will continue to be the exclusive salesforce for Yahoo’s Gemini ads platform. Integrating the sales teams with those responsible for engineering will allow both companies to service advertisers more effectively. Microsoft and Yahoo plan to begin to transition managed advertiser sales responsibilities this summer.
http://info.yahoo.com/press-center/article/microsoft-yahoo-agree-amend-search-130000454.html