Razvan Dubau over at Extragsm posted a how-to on using an ESP8266 module as a wireless switcher:
A custom firmware to transform the ESP8266 wifi module into a wifi http based switcher
GPIO02 is used as an output pin. You can connect a led or a relay and controll it by a button added to GPIO00. Also the firmware provides a web interface and a simple API that will controll the GPIO02 state.
The codesource is available at Github.