Introducing Raspbery Pi à la mode (Connect Pi to Arduino)

Here are the features including a few extra goodies:

• Flexible power. Can be powered directly from the Pi, standalone with a battery or wall-wart, or USB power. This is important if your shield takes more power than the Pi can provide or if you want to undock it for standalone operation.
• Programmable via the Pi’s UART on the GPIO pins, or an FTDI USB-Serial adapter or ISP.
• Header for connecting Fastrax UP501 GPS.
• DS3234 Real time Clock. The Pi doesn’t have it’s own battery backed RTC. You can set a program in the AlaMode to report the time to the Pi via serial or I2C
• Micro-SD card slot. Useful for datalogging, and big-memory  for your Arduino applications
• Row of Servo Headers connected to the PWM pins with a configurable power and ground rail

http://baldwisdom.com/introducing-raspbery-pi-a-la-mode/