Theoretically if the Bitcoin market was 100% efficient the exchange rate of fiats should be the same in Bitcoin pricing. That is definitely not always the case, and if someone has a global bank accounts they may be able to take advantage of these arbitrage opportunities.
In the last 2 years this gab has tightened which is expected. Here is a current example
Looking at the Canadian dollar. (Ignoring MTGOX)
Virtex = 875 CAN to buy 1 bitcoin
BtcStamp = 861 USD buy 1 Bitcon
CAN To USD conversion 90.5 CAN to USD
All prices as of the time of this post. (Ignoring commission and conversion charges)
So if you bought 10 Bitcoin in Canada = $8750 CAN invested
Sell in the USA 10 Bitcoin = $8610 USD
Convert to CAN dollars at 0.91 = $9461 CAN dollars
So you would have a $710 profit (Approx 8%) bringing the funds back to Canada less commission. DO this enough and the spread should theoretically tighten to not be profitable.