b/c like it or not, gox has 1000's of real bitcoins, that users cannot cash out.  Well for cash they can but not coins.  ANyways Mt.Gox made bitcoin to where it is today as an exchange.  They do the most volume of trades per day.  And like it or not, the other exchanges will follow.  They are the Nasdaq of the bitcoin world.  Imagine if NASDAQ said you cannot sell your stocks because there is a problem with our system.......Matter of fact.....Here we go..490.....480