This is a really good idea. If they can get the right games on board. Also if they can figure out a way to deal with taxes. Diablo 3's real money auction house was basically shutdown because the US government wanted their piece of the pie and it sounds like Blizzard didn't have a real way to do that.
Thats true,if they can get some strong partnership with the big developers,it will be much easer,but even if they start with smaller ones,team and project are strong enough to overcome that obstacle.