I have finally cobbled together a fully wireless two-way controller using the Arduino Esplora board released in December. It uses an XBee radio for two way communications, straps on a battery pack, and has a sketch to send and receive commands and send joystick & button presses.
In previous posts, I documented the Arduino Esplora "display" interface headers and I interfaced an XBee radio to two of the data lines on that header (which happen to be the hardware TTL level serial port). The program communicated to a PC connected to another XBee via a USB board. The solution was not truly "wireless" as the Esplora was still connected to a PC for USB 5 volt power (the designers did not make any known provisions for power beyond the USB port on the board).
I also needed a battery source for 5 volts. A nice Lithium Ion battery pack would be ideal but again attaching such is not in the current Esplora design. So I hacked it. I took an Energizer USB battery, usually used to power a cell phone in a jam and fed power into the USB port. I attached it with a rubber band as time was rather short.
The code is again available as Open Source on my GitHub repository at https://github.com/TheKitty/EsploraSerial under in the EsploraXbeeController directory. I think it's about 10 kilobytes or so, plenty of room to expand the functionality.
Here is a video of the controller in action:
Where should the project go next?