(Yesterday, Microsoft announced that voice search capabilities were being expanded for Live Search.)
Yahoo is also opening up mobile search in the same way it has on the desktop with Search Monkey (the unofficial name). Ott told me that publishers and site owners could do this once for both desktop and mobile or they could do something separate for mobile as well. (Think: dynamic feeds that repond to mobile use cases.) According to Ott, this will likely impact (though not determine) mobile search rankings.