I think Leviton makes a unit like that. Smarthome used to or still does have a "Togglelinc" which is sort of like what you want. These units have special requirements like having a neutral line in the box, and the togglelinc (I hope that's the correct unit, [I'll search a little when I get a better internet connection]) doesn't operate exactly like the old flip switches, but looks about the same.
Dan is correct that X10 does not have what you are looking for, but the x10 protocol is still used by other companies.
