The World of Warcraft Website has some thoughts on Blizzard's stance on gold selling, following the announcement of the Guardian Cub item that will facilitate cash for gold transactions:

With all that in mind, we come to the new tradable Guardian Cub pet. By letting players trade this pet, we’re giving those who want to participate in the Pet Store without spending real money a way to buy the pet with gold instead. This also means that players can buy one for the purpose of trying to sell it in-game, creating the potential for players to exchange real money for gold in a way that does not lead to account compromises. Of course, all that comes with the pretty important caveat that demand for the pet will be finite, and there’s no guarantee you’ll be able to find a buyer.

While this one little pet can never come close to “solving” the above issues with third-party gold selling and account compromises, it may help us determine whether we’re able address these ongoing problems in a safe, creative way that ultimately has a positive impact on the game experience overall. Our hope is that through all of our increased efforts we can make World of Warcraft a safer, more secure, and more enjoyable game for all of our players.