I haven't put the firmware on Github for the ESP8266 in the Sonoff device, because it is just slapped together to get the project started. When I really start to work on the full featured ESP8266, I will put it up on Github, but for now, here is the firmware for reference:

#include <user_config.h>
#include <SmingCore/SmingCore.h>

#define RELAY_PIN 12 // GPIO12

Timer procTimer;
bool state = true;

void onSerialDataCallback(Stream& stream, char c, unsigned short charCount)
{
	Serial.print("0x");
	Serial.print(String(c,HEX));
	Serial.print(" ");
	Serial.print(charCount);

	while(stream.available())
	{
		char cmd=stream.read();
		if(cmd == 'N')
			digitalWrite(RELAY_PIN,true);

		if(cmd == 'F')
			digitalWrite(RELAY_PIN,false);
	}

}

void init()
{
	Serial.begin(115200);
	pinMode(RELAY_PIN, OUTPUT);
	Serial.setCallback(onSerialDataCallback,true);
}