There are many ways to go about automating your home. This one uses the existing AC wiring for the communication.

Xtenscape was developed by Scott Hather which allows you to take control of this X10 technology using a free custom built app. X10 is an international and open industry standard for communication among electronic devices used for home automation, also known as domotics. This process uses power line wiring for signaling and control, where the signals involve brief radio frequency bursts representing digital information. A wireless radio based protocol transport is also defined.

As for the software, there is a a Windows and Mac version available. The idea of the software, which is free to download for iPhones (note the X-10 hardware [modules] are not), manages control signals by creating a ‘piggy-backed’ system whereby the electrical current running through your house is used to tell a specific receiver to switch on or off. So simple your Granny could do it and all available through your iPhone.

System requirements:

• Intel-based Apple Mac or Windows PC (98 and above)
• Java 1.5 (included on a mac, download for PC)
• Windows only: Microsoft Dot Net 2.0 framework
• CM11A or CM12 X-10 Control module (any type, UK, USA, Euro etc)
• At least one Appliance module or Lamp module
• Spare COM port or USB port (COM to USB convertor)

[via Hacked Gadgets]