But that is not escrow service by a third party.

The Bluepaper says,

"The irreversible nature of blockchain transactions is an important security feature, although there are many cases where users may not be comfortable sending their tokens to another individual without a way to get them back if the other user does not hold up their end of the agreement. The Steem blockchain provides a way for users to send coins to each other with a third party designated as an escrow service. The user acting as the escrow service is able to determine if the terms of the agreement have been met, and either allow the funds to be released to the receiver or returned to the sender."

The current transfer mechanism you are referring to does not allow for recovery of coins sent in the event the agreement is not honored.

If an escrow service is available, then Steem users will be able to sell and buy goods and services on Steem blockchain.