WAR declares war on Gold Farmers
Here's the thing. If you know people are going to be farming and selling gold, why not just build your game in a way that takes advantage of the practice, instead of employing feeble, expensive, and (I predict) useless tactics that prevent the sellers and the buyers from playing the game they want to to play. If I were building an MMORPG, I'd build a safe system for buying and selling gold right into the game, add prestige incentives for use, and take a slice right off the top. You have to START with that in mind, because depending on your game, too much gold too quick could certainly mess things up.
I think this falls into the category of, "World of Warcraft does it this way, so this is how it must be done." Of course, WoW doesn't really stop gold farming, but smaller companies will try to 'succeed' where WoW failed. Have fun guys.
Games are about what the players want, not your 'vision' of gaming utopia. If players want to buy gold, I say sell it to them.