No. but mtgox sell for users with high price and buy from users with low price.
But it's higher....
I too looked into this and found a couple things. There are fees you will have to pay each time you go from one site to the other. And there is a lag time also which might play into the factor of loosing a little bit more $. BUT it might be a good deal to make a little here and a little there. It will add up
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Yes, MtGox especially seems to have a terrible lag time, coinbase is VERY fast.
It's a great question and this method could be of some benefit when there is a difference between btc-e,bitstamp and coinbase but please exclude mtgox as money in there can't be withdrawn in most of the world.
The reason why Btc-e is Lower in price is the difficulty to fund your account (and the associated high fees of bankwire,funding to perfectmoney etc...) .
BitStamp and Coinbase have the fastest transaction times, but their price is very close indeed. If you're willing to wait, MtGox could be a killer money maker. Waiting is OK if you have funds to play with while you're waiting and the money is settling.