huobi is leading, but other exchanges shouldn't follow if they think the price is going way too high or if things look fishy. just look at btc-e, they don't seem to care that much about what other exchanges do.
I don't know if this is true but CompNsci says btc-e told him they have stopped dealing with US banks and customers. He claims it's difficult for US people to get money into the exchange and nobody is trading. The volume is very thin so their price compared to other exchanges is irrelevant. I know Bitstamp recently added a questionnaire asking if you are from the US, and demanding answers to questions if you are.
https://bitcointalk.org/index.php?topic=1236832.0While they have not formally announced it, BTC-e recently stated to me that they are no longer dealing with US banks or customers.
This would explain the lower price of BTC on that exchange as USD would be relatively more scarce there.