Yahoo (NSDQ: YHOO) is to become T-Mobile’s exclusive web search provider across much of Europe from March, the pair announced in Barcelona. T-Mobile had already started using Yahoo’s oneSearch in the UK in January. Once upon a time, Google (NSDQ: GOOG) was the operator’s preferred choice for its Web ‘n Walk mobile web offering. But last year’s updated version of oneSearch (both an app and a hosted web service) impressively caters for mobile browsing peculiarities more so than Google’s mobile search, which has recently made some updates to emulate Yahoo’s approach. Yahoo today said oneSearch is now on 29 worldwide operators, serving 600 million subscribers, including AT&T (NYSE: T) in the US and America Movil’s 16 Latin American countries. Reuters (NSDQ: RTRSY) further spins the gains Yahoo is making over Google in this area. The company could offer its current suitors an increasingly strong mobile portfolio. More coming from Yahoo during Mobile World Congress…