Most of them use VPN's to mask where they are actually logging in from so blocking Chinese IP blocks does absolutely nothing to help the matter. The only thing that will stop the Billion dollar a year industry is to make it where gold is not tradeable to other players...and that would kill the AH and any other ways for players to make gold with professions and such. Now, if people stopped buying gold, the businesses would stop but that will not happen when there are those to cheap to earn their own way in the game that throws gold at you already.
when all else fails, read the STICKIES.