ZigBee is a low-power communication system using digital radios. It’s intended to be easier to work with than Bluetooth. Adafruit recently added an adapter board for Digi’s XBee product line and has put together a great how-to to show the devices potential. Using two XBee radios and adapters you can wirelessly program an Arduino board. This would be great if your Arduino was installed in an inaccessible area or maybe it’s over 100feet away from where you’re working. The radios do serial communication just fine. What the how-to covers is getting the reset line working so the Arduino can restart automatically after you program it. Once the radio pair is configured properly, it will pass the RTS line state directly from one device to the other.