Is Diablo 3 going to be region based? If so, can you choose freely? Can you transfer characters? Can you switch at any time?
Reason I ask is pretty much the RMAH, I can foresee a lot of poor people in Europe trying to sell stuff, while I can see lot more potential buyers in the NA region.
Your currency-based auction house is bound to the region your account is associated with. However, you can play on NA Servers if your on a eu bnet acc and vice versa.