Arbitrage in Bitcoin exchanges
To answer your question let me give you an example of what some people do in order to try and take advantage of market arbitrage with Bitcoin.

As you know, Bitstamp and BTC-E are two of the biggest exchanges that are trading Bitcoin. If you look at the BTC price on BTC-E you can see it is always lower than that of Bitstamp. 

If you were to go to Russia (or know somebody in russia that trades bitcoins locally) they go by the BTC-E price there. So, if you find a guy in Russia that can sell you coins at BTC-E price, if you are located in the US you can sell your coins here at Bitstamp's price. Same goes for Huobi (which is in china). 

In order for arbitrage to work you need to know people in different countries who can sell bitcoins locally for you at that market price.

So go out there and make those connections whether it be in the trollboxes, forums (bitcointalk) or other means.

Hope I helped.