Yahoo and Microsoft announced today that they had received regulatory clearance from US and European regulators. Under the pact Microsoft’s Bing search engine will power Yahoo Search and Microsoft’s AdCenter search advertising service will provide search ads to Yahoo Search. The companies had announced the pact in late July and reached a finalized agreement in December. The companies have set a goal of serving results from Bing in Yahoo Search in “at least the United States by the end of 2010”. The transition to serving ads from Microsoft’s advertising service in Yahoo Search is planned to occur “prior to the 2010 holiday season, but may wait until 2011 if they determine that the transition will be more effective after the holiday season”. They expect a full transition by early 2012. According to the companies, Yahoo will build its own “search experience” on top of Bing’s search results by “integrating rich Yahoo! content, enhanced listings with conveniently organized information about key topics, and tools to tailor the experience for Yahoo! users”