@ BroHogan and Phil.H.
BroHogan is probably right, I got it mixed up when i replied to Jonathan about the frequencies. I've heard that X10 in North America use 310MHz as well. And it's the 310MHz receivers that are hard to find, not the 315MHz ones 
Does anybody know if changing the frequency of a receiver is as simple as replacing the crystal and the length of the antenna?
If you want to try receiving RF or IR BroHogan, you should use my libraries in stead of the other playground ones for the PLC as well. The playground libraries rely on using blocking code and delays. This works fine if you are only doing one time critical task a time (receive PLC f.ex.), but becomes very unreliable if you want to receive RF and send PLC at the same time (sending dim commands f.ex.). Or if you want to do what I'm doing, support receiving RF and IR at the same time, while both sending and receiving PLC and serial messages.
My PLC library also uses a buffer, so you don't have to wait until the PLC signaling has completed before issuing the next command (this is critical since sending a PLC command can take up to a second).
And yes, all my stuff operate at 433MHz. The protocols are the same though. I've used the American data sheets when doing research for my project.