Its is possible, to play an character animation by voice command (PLAY) then the animation play, and voice command (JUMP) and the character animation jump Im unsing Unity for IOS and Androis aplication. Heres what im trying to achive. http://www.youtube.com/watch?v=9KwAdsV8PE4&feature=g-hist
I don't think unity has voice recognition built in. But I bet you could find a mono/.net library to integrate and get the functionality. It might be a bit of work to get such a library up and running though...