I am new to Smartthings and reluctant new user of the arduino.
Small trap for new players is the shield will not work on a arduino Mega2560 with the sample code.
The software serial driver RX function will not work on pin3. See http://arduino.cc/en/Reference/softwareSerial
if you link the RX pin over to another pin such as 11 and modify the software to suit it all works fine.