I've just started working on some experiments to help me put together a home automation system.
I'll be messing with relays, ethernet shields and PoE etc, maybe some touch screen TFT panels, who knows!
Feel free to watch my progress at http://www.anotheroldgamer.com
I am investigating to do the same. At this point, it seems I will be using a Raspberri Pi model B with a Chalkboard Electronics touch screen as the UI (perhaps running something like FreeDomotic so I don't have to write a lot of code, something I'm neither used to nor proficient in), and Arduino Ethernets on every room.
Because I want a producer-consumer model, I'd love to use something XML-based to talk between the nodes.
Any ideas or comments appreciated.