I can't seem to find any rules on it when it comes to pvp. Lost a bg the other day because suddenly a horde shamen multiboxer showed up and we were just killed over and over again. Before that there was a multiboxer horde in stormwind killing the auction people over and over.
I've also heard people pay to be able to multibox?
there are no rules for multiboxing. as long as they're not breaking the rules that are for all players. and most multiboxers donate at least once on each account so they can avoid the que.