It's funny people are complaining about free money from the arbitrage
Transfer $$$ to bitstamp to buy bitcoin
Transfer bitcoin to mtgox to sell for $$$.
A quick 6+% profit, after deducting the transaction fees from the two exchanges.
Sure, withdrawal delay with mtgox. Let say, 3 months to cash the money back to your bank.
What's the big deal? It's still an easy 6+% profit over 3 months.
Now, look at how much the bank pay you in saving interest per year?
The reason that arbitrage like this 6% spread
still exists without fluctuating much is because no one is
capitalizing on it so as to close the gap, which then further
maintains this arbitrage since MtGox's inability to payout
prevents capitalists to
risk the uncertainty of withdrawing GXD (Gox USD as a fellow member labeled it) into realized USD.