Tony Northrup, co-author of the recently published Home Hacking Projects for Geeks, has a good introductory article on X10 Home Automation Technology at the O'Reilly Network.

While I'm not sure that you need to be a "geek" to enjoy do-it-yourself automation, I definitely agree with his assessment that being filthy rich, and having someone else set it up for you, is a viable alternative approach.