Ok, finally I found a simple and general method to work with basically any off-the-shelf remote controlled power sockets. The idea is to first use an RF receiver + sound card + audio recording software to sniff the remote control signals, then 'play it back' using an Arduino + RF transmitter to simulate the remote control. I wrote a blog post about this method, which you can find at:
http://rayshobby.net/?p=3381
It also includes a demo of Internet-based control of devices using an existing OpenSprinkler board.
Hope this is useful 
-Ray