"What I would like to know is how does this effect your electrical bill?" Not being an expert, I can only imagine that this system would use as much electricity as a normal router or hub would. Would this type of system add any kind of noise to the line, since its passing a signal other than just drawing power?

It wouldn't. You would not be using any power from the wires you have in your wall except for the transievers on either end that put the signal on the wire and take it off. This idea is already very big in Europe. Lots of US poower companies now use a very similar technology for meter reading. The new meters are addressable. The power company looks up your meters unique number reads the meter and sends you a bill......or turns off your service as the case may be. The whole process is automated. No more meter readers. Further some power companies are transmitting internet traffic over their existing power transmision infrastructure. None of this effects anybody's electric bill. It's just another way to send a signal.