World of Warcraft Forums
have word that paid faction changes are now
Blizzard Support's Faction Change FAQ
has all the details, and word is:
"After purchasing a Faction Change for a character, a player can choose any race
of the opposite faction that is compatible with the character’s class." They
also say that they will also be offering a paid race change service going
forward, and more details on that will be revealed at a future date.