Wirelessly controlled power outlets are best suited for switching on/off appliances as they do not need cables and only the remote control needs to be interfaced to a microcontroller. Design is electric -shock -safe as the high voltage modules are not opened.
Arduino microcontroller greatly simplifies the task, because it is a standard board that can be easily reprogrammed. Arduino could be connected to a PC, WiFi router with USB running OpenWRT, or direct connection to Internet could be done via Arduino Ethernet shield.
Picture below illustrates how home automation box could look. There are external sensors attached to Arduino, PIR, photodiode, sound level monitor, 1-wire temperature sensors DS18B20
The first attached pdf file contains details how to program Arduino for steering the wireless power sockets.
Second pdf file describes how to connect sensors and relays.