Home automation protocols in Europe

There is Common External Message Interface (cEMI) which should be independent of the physical layer. Openremote has also a nice technical overview of KNX.

Z-Wave is the facto industry standard for wireless home automation (the next X10), and there are hundreds of products Z-Wave enabled. Digikey has boards and dev kits, and there is even a small power plug linux box with Z-Wave and ethernet embedded.

http://www.z-wave.com/modules/Products/?id=66&chk=94b8927269761c1a0c94de9268724ddb

http://web1.zen-sys.com/modules/Products&Techonology/?id=33&chk=7c18247ff46da755b3d1753888e2a342

http://www.tricklestar.com/US/300ZW_US_W.html

http://www.ionicsplug.com/stratusplusplus.html

http://www.digiwave.dk/en/programming/an-introduction-to-the-z-wave-protocol/

http://www.digiwave.dk/en/programming/an-introduction-to-z-wave-programming-in-c/

http://www.smarthome-products.com/p-625-homepro-zcu201-z-wave-usb-interface-euro.aspx

http://plugcomputer.org/plugforum/index.php?topic=1462.0