Liquidity goes both ways. Mtgox is filled with money that nobody wants very much. Do you think that the people who offer to pay 5-10% more than they would have to on other exchanges and still don't get their orders filled agree that the liquidity on MtGox is good? The trade volume clearly shows that the liquidity is there on Bitstamp if you put up an order in the right price range.
I'm talking about (fiat) Market liquidity not about some panic buyers who move the price a few percentage points up.
Market liquidity: "In business, economics or investment, market liquidity is an asset's ability to be sold without causing a significant movement in the price and with minimum loss of value."
See:
https://en.wikipedia.org/wiki/Market_liquidityWhat happens if 50k BTC would be purchased on MtGox to sell them on Bitstamp?
Answer: It's not possible because their is not enough fiat liquidity (money) on Bitstamp.
Although there is little trading volume at the moment on Gox so this can change every minute.
Do you seriously think that everyone can sell his fiat in the case of a buy-panic on Gox and sell the bitcoins then on other platforms without fall back to single digits?
I'm glad that normal people not give up so easily as some people do here. I can not believe that some one charge off Gox and believe all would just continue. At least 60% of the fiat money that has been invested in the last years in Bitcoin is on Gox. If this would be gone, then good night. The last one turns off the light. A massiv loss of confidence, the Bitcoin would not recover for years if ever.