looks like some pack of exchanges sell Bitcoin he not really have
when people start withdraw Bitcoin will happen MtGox2
NEVER KEEP YOUR BITCOINS IN ANY EXCHANGER!
It's easy to say but very hard to do. Now store bitcoins in an offline wallet and withdraw coins to the exchange before each transaction is not a problem. But how to do this when the transaction price is $ 50 and the queue to confirm the transaction a few days?