Ok. I have spent several hours unnecessarily trying to write to an zigbee with an Arduino program. I thought that I had to bring the zigbees into command mode, in order for them to be able to send data between the radios. After becoming somewhat frustrated I became smart enough to just try Rob's code.
And this is where I am so far:
I am just using an LED at this second. And the controller zigbee is still hooked to a maxstream usb board. So next step, switch out the maxtream board for another arduino board.
OK. My switch from the one arduino board is now causing my LED to blink. Yay. This was my setup for the 2nd arduino + breadboard: