I've been watching BitCoins for the last few months, and noticed that MTGOX's price per bitcoin is always higher than the price per bitcoin of similar exchanges, (eg cavirtex.com, and bitstamp.com).
Why is this? And why wouldn't people just buy them at another exchange, send their bitcoin to MTGOX, and cash out for an automatic (from what I've seen) 10-15% increase in what they invested?
I know they were the most popular/liquid site for bitcoin's until just recently, but I've heard that BitStamp has surpassed them.