arduinopro:
So now I'm confused because the ArduinoXbeeShieldhttp://www.arduino.cc/en/Guide/ArduinoXbeeShield says that you wouldn't have to configure two arduinos if you use Serial.println() to communicate with each other.
I'm not sure what they mean by that. As far as I know you have to configure the xbee modules so they know which xbee address to send packets to. I.e. if you have two xbee modules A,B with serial numbers like SH(A),SL(A) and SH(B), SL(B), you need to set the destination address for each module to point to the other one. I.e. DH(A)=SH(B), DL(A)=SL(B), and DH(B)=SH(A), DL(B)=SL(A)
See further down the page you linked for more details on how to do this.