We put together a Playstation DualShock Controller Shield on Tindie: https://tindie.com/shops/DexterIndustries/arduino-playstation-dualshock-shield/.
The project is open source and the design can be found on our Github repository here: GitHub - DexterInd/Arduino_Playstation_Controller_Shield: A playstation controller shield for the Arduino.
We want to get some feedback, and we're hoping to raise enough to do a production run. We would love to hear what you think!