I automate my home lighting with X10 modules bought from Radio Shack and Home Automation Systems. I also have evaluation versions of some X10 computer interfaces that I was beta testing for X10 USA.
Click here for a more detailed description of my current home automation setup.
I'm currently working on a piece of software to interface with a TW523 computer interface with an RS-232 serial adapter. The computer controlling it will be a PC running Linux or a Sun workstation. The interface doesn't have the ability to store timer events or macros, so the X10 i/o will be completely computer controlled. The computer will manage and schedule X10 events. Also, the interface can receive X10 signals and pass them to the computer, so the computer will be capable of running X10 macros as well.