I started my research right after Halloween and I came across a couple different options, but I settled with the following combination of hardware : arduino + adafruit wave shield + ioBridge + wifi bridge + solid state relays (SSRs).
The xmas-box is enclosed in a small plastic tool box. I have place it on my deck under a roof ( it is not completely weather proof). The tool box has “3 levels.” The bottom is where all the SSRs and AC wiring are located. The middle (the inside tray) contains the wall warts for the arduino (9v), ioBridge (5v) and Wifi Bridge with power. The top level contains the Arduino board, the ioBridge module and the FM transmitter.
Video of the Christmas Light Controller in action!