It would be cool to use the Snowball throwing script to create a Dodgeball room in the Battle Arena.
All you would have to do is change the snowball image and then add a script that checks for the hit-with-snow animation to warp the person out of the game.
You could do 2 v. 2 or 3 v. 3. You could have a line in the middle that the players can't cross over or they are warped out.
Or, you could get really crazy and let two guilds play against each other, like in guild spar. I suspect that the viewport on the iPhone may be a problem for this, so it may just have to one big open room with no divider.