I am running Actiontec brand Powerline network adapters. These are the cheapest i have seen and available at best buy stores for instant gratification. No idea if they are plugged into the same circuit. Works fine for my purpose which is to "hardwire" a 2nd wifi router into my network. I would of course prefer having CAT 5 run, but its an 1860s stone farm house. Wiring and solid 18" stone walls just don't go together. wifi signals also do not pass through the stone walls very well.
Anyhow, I have the primary router jacked into one Powerline adapter, and at the other end a secondary router which gets me wireless coverage on my porch, and over by the pool (which was absolutely necessary so I can access PPOT while sunning by the pool
). For basic web browsing, this works perfectly. Haven't tried multimedia stuff.