Batman Emoji Theme is a BytaFont 2 theme in Cydia that will convert a good amount of Emoji smilies to resemble Batman. Don't get too excited messaging friends with these, as this is a theme, so only people looking at the device it is installed on can see the new Batman look.
The theme is free and requires BytaFont 2 (also free). After downloading both Cydia packages, open up BytaFont 2 > More Tab > Emoji> Batman Faces, and check out your new Emoji look. Want your friends to see Batman Emoji when you text them? Encourage them install this theme as well.