With the falling cost of semiconductors and the emergence of single chip radios, it is now possible to incorporate wireless communications into cost-sensitive embedded systems. Since the airwaves are an uncontrolled medium, embedded systems engineers must take care to assure that the wireless communications is reliable and easy to use. Self-healing wireless mesh architectures, in which devices in the network automatically relay messages on behalf of their neighbors, are an excellent choice for embedded systems: they are highly reliable and easy to set up.