This arbitrage, and more to other exchanges, should provide some damping to the dump/panic buy movements on gox. Maybe the next bubble (entrepreneurs having temporarily too much faith in bitcoins rapid world takeover) will be a tad more leant back.
I see no panic at Gox. It has 4x the 24hr volume now, and buyers have "eaten" through ~ 6000 bitcoins at a $145 ask price in the last 24hrs alone. There's been a lot of resistance more recently on the way up ($145/$146 levels, for example), but the buyers have continued to push through.
No one seems to be looking to sell at $142/$143 levels anymore, regardless of whether there's much on the order book. You get a lot of slippage selling into the order book now... would be much better off just putting up a wall at $146 or something.