I was thinking something more automated and web based.
Like a regular exchange where you could log in and get the current exchange rate.
The rate would be based upon your preferences such as high level of trust, speed, or rate.
People who are willing to trade can set up automatic rate changes to move with the price automatically instead of needing to be on chat saying "I'll give you X for Y".
You just set up your exchange abilities (Dwolla, direct deposit, Wells-Fargo, ING, etc) and the rate you are willing to trade and let the server take care of changes in price and all of the rest.
It would be just like logging into MtGox but your money could be traded by several different people. You would rate your experience afterwards to let people know how trustworthy someone is.