As Anthony said X-10 operates on powerline and has either IR or RF receivers.
The big gotcha here with the Pronto RF and X-10 RF receivers is that they operate on diferent frequencies (418mhz and 310mhz respectively). The 3000 WILL NOT operate X-10 RF receivers out of the box. You need either the IR543 gateway (as Anthony said) or and RF to RF converter and an RF receiver. The RF receiver is no big deal $20.00 from any X-10 place. The problem is the RF converter.
[Link: laser.com] has a ton of really good info on RF (including how to make a converter)
