If you're a WoW player, you're one of two things. You're Alliance, or you're Horde. That's it. That's where the line is drawn. Or... it was. Pretty soon, that won't matter anymore.
Blizzard have begun work on a new service that will let players switch sides. Alliance to Horde. Or Horde to Alliance. Whichever way you want to turn your coat, you'll be free to do it.
There'll apparently be rules governing the use of the service, but in a nutshell, here's how Blizzard explain it:
There's still much work to do and many details to iron out, but the basic idea is that players will be able to use the service to transform an existing character into a roughly equivalent character of the opposing faction on the same realm. Players who ended up creating and leveling up characters on the opposite factions from their friends have been asking for this type of functionality for some time, and we're pleased to be getting closer to being able to deliver it.
So there you have it. Sounds great for those itching for a change, but I can see some more hardcore role-players within the community being a little upset.
Faction-Change Service in the Works [Blizzard]