See figure 4 in the datasheet). translate the 3.3V signals on the XBee side to and from the 5V signals on the Arduino (I *think* the RPi IOs run at 3.3V, so those can just be connected directly).

Digi has unveiled a new range of XBee modules that now support 802.11n Wi-Fi, allowing Arduino developers to easily add 802.11n Wi-Fi support to their creations with the addition of the new ...