Info on the guts of the esp8266 EcoPlug/WorkSmart CT-063w WiFi Smart Socket with energy monitoring made by KAB, available from Wallmart. Also sold as WiOn from Pegasus Lighting. Module appears to be used in wall switches, as well.
More info on local control of Orvibo S20 Socket
Good info on hacking/spoofing the Orvibo S20 WiFi socket. Unfortunately, it appears that the security of the cloud service is (was?) really bad.
Report on using Sonoff with alternative Sonoff-Tasmota Firmware
Source: Review of Sonoff RF Bridge, Sonoff 4ch Pro, and Sonoff POW with Sonoff-Tasmota Firmware
Sweet new project!
ESP8266-HomeKit – HomeKit server on ESP8266 RTOS with an API approach