MLB has an app (iPhone and Android, AFAIK), that features video replays of significant plays (essentially the highlights that the MLB puts up on the game recap

MLB has an app (iPhone and Android, AFAIK), that features video replays of significant plays (essentially the highlights that the MLB puts up on the game recap page on their site) and streaming audio (and video, for additional money). There's special features for when you're actually at the ballpark, but I've never used them.