This is why we need a decentralized exchange, owned by nobody. The Mastercoin Foundation is creating the first. And I am quite certain there are more in the pipeline.
Centralized exchanges will be a remnant of the beginning stages of Bitcoin.
I haven't read up much on the concept of decentralized exchanges yet. I'm curious, how would a decentralized exchange handle the process of moving the fiat cash among the users fast enough to act as an exchange?