On mop, horde and alliance could communicate with each other, why not cross faction rp?
Zones that are empty and or somewhat neutral can be used, such as gilneas or areas a bit away from goldshire or other small towns.
Juat wondering if anyone had given this a thought.
There is someone I know on sarg realm who role playes unintentionally, playing his character as if he was said character.
Roleplaying palace does cross faction RP from time to time. Cross faction talk is pretty much a bug I won't like being fixed anytime soon :P No harm in having it around really.