Hi,
I thought this may be of help:
http://www.glacialwanderer.com/hobbyrobotics/?p=9
"Using Relays with Arduino – Turning on the Lights"
It's basically about being able to use an Arduino board to control a 240/110v light (or anything else with a wall plug).
I will put anything else on here i bump into, and put any useful code up too.
cheers.