A really nice (and not so expensive) domotica system is Velbus. It has been created by Velleman. Checkout http://www.velbus.eu
They've got almost a solution for all systems, and even a software center.
But this software center is 'too' expensive.
Once you like the opensource software world...
Velbus is working on the system 'CAN bus'.
And i'm thinking to see how i can implement this in linuxMCE.
Is it difficult to do this?
Or is anybody willing to have look a it?