Just a thought

[avid_consumer]

maybe exchange of BTC for USD should be just as decentralized as BTC itself. 

the concept of an exchange should break down so that everyone is an exchange.  the current bid and offer come from the network, just like the ledger itself.  if the community is willing to decentralize trading itself as they are the integrity of the currency as a whole, maybe that's the next step.

[bitv]

That's certainly possible I'd say.

I think it's not implemented yet, because everyone already has their chance to open a new exchange. You don't have to use Mt. Gox if you don't want to etc., it's your choice what you pick up.