Yahoo has begun testing organic and paid search listings from Microsoft. Up to 25% of its search traffic in the U.S. may see organic listings from Microsoft, and up to 3.5% may see paid listings from Microsoft adCenter. I guess you could say that the early stages of the Search Alliance's transition have begun. "The primary change for these tests is that the listings are coming from Microsoft," says Yahoo's VP of Search Product Operations, Kartik Ramakrishnan. "However,