It works like this: Trusted parties could send some kind of random amounts of bitcoins from one seemingly random address to another both controlled by the same party or one controlled by another trusted party.
How do the parties establish their trust?
Have you read about green addresses? Green addresses are owned by entities which have a large interest in being trusted to not double spend their coins. In this way, a dealer can choose to trust the received funds from a green address to not be double spent and he does thus not need to wait for the six confirmations to deliver the purchased product to the customer. Green addresses are owned by the largest bitcoin companies in the community like Mt. Gox.