Blizzard is ACTUALLY trying to prevent people from gaining real life money from this...
They want people to acquire virtual money, and spend virtual money only mainly.. so it's a closed loop system..
Essentially this is quite interesting, since, you never have to spend much money for items, cos u can sell the stuff u dont need for virtual money and buy other stuff.
Well, keep in mind though, keeping money virtual should encourage players to use it more frequently (either buying something from the blizz store or the RMAH); either way, Blizz gets a cut. You never need to dip back into your wallet so long as you continue to make smart moves on the auction AND are able to absorb the Blizz fees.
As someone who works in the bond market, I find the potential here really interesting.