I've been using Arduino and OpenHAB to start building home automation. I wrote up a description of my first simple setup here. I thought other Arduino users might be interested, or could give advice on some of the stumbling blocks.
This setup allows you to make your own wireless Arduino sensors and host the sensor data on your own server at home, which you can access via smart phone. You can also use it to chart sensor data over time, actuate outputs connected to your Arduino, send emails/notifications when sensor value reaches some defined point. Very neat.http://goo.gl/GtxLlN