Engineers at Yelp have put together an Arduino and iPad controlled Keg-o-rator.  By swiping their RFID they can track how much a person is drinking, collect statistics about how others enjoyed the beer (by rating it), and maintain a leader-board of the office.  Everything used in the project is based on off-the-self components.  My guess is that they are communicating between the iPad and Arduino over the iPod Dock’s i2c interface.  It looks like they are using the PodGizmo iPod Dock Conntector Breakout board available at Kinetka Systems.  Drink up!