Voice-powered mobile user interface developer Vlingo announced the completion of a $20 million Series B financing round led by web services giant Yahoo, which today also named Vlingo its software partner on the new oneSearch 2.0 text- and voice-enabled mobile search service. According to Vlingo, proceeds from the funding round--which also included existing investors Charles River Ventures and Sigma Partners--will be earmarked to fuel international expansion and continue its R&D efforts.