I've been playing this great puzzle game on my iDevice called Piyo Blocks 2. It's so simple to play and unbelieveably addictive! And it has multiplayer features including 2 player battles over local wifi and bluetooth, and online challenges through the OpenFeint network.
If you want to play Piyo Blocks 2 against me, you can download the game from the AppStore using the link below. My OpenFeint username is "fullfilth", if you think you can beat me in a challenge!!