This little project is about communicating between a Mac (or Linux) system and an AVR MT 128 using an XBee device for wireless communications.

So, what's an XBee? It's a small wireless transceiver that operates in the same 2.4GHz spectrum as WiFi (and doesn't interfere at all), implements the IEEE "ZigBee" standard, and is manufactured by MaxStream. They are primarily designed for wireless control applications, but have all sorts of uses. The simplest use for a pair of XBees is a wireless serial cable replacement. Depending upon power/range, you can buy them for $20 or about $35 from DigiKey. In the picture below, the XBee is the blue device mounted on the circuit board.