RjDuino allows you to control an Arduino with your iPhone running RjDj. I definitely want to try out this project, especially the pitch controlled LEDs.

Using a custom RjDj patch to control an Arduino. Made possible via the “netsend” and “netreceive” objects in PD, which are also usable in RjDj. The interface with the Arduino is made through the Firmata firmware in combination with the PDuino library.

In the Maker Shed:
Makershedsmall
Arduino Family
Make: Arduino