I think its better to have the network vote about it instead.
So either the sender gets the cash back or the receiver gets the cash. Like a "real" escrow.

I wrote a thread about it: http://bitcointalk.org/index.php?topic=4856.0

Then its not possible to use the money as a "threat tool" either:
For example:

A sells a laptop without power adapter because A needs the power adapter to a new laptop.
B buys this laptop and in the business deal, its specific that power adapter is NOT included.
B then says "If you dont send the power adapter I will never release the money."

Now B is forced to send a power adapter to get the money for the laptop at all.
B will still lose the money even if A don't send any power adapter, but he still can force many extras from the seller for same money. And in this way fraud the seller.


With my solution with secure chargeback, it will never happen. B buys something from A. A sends the freight number as a reply to the transaction. If B now protest, everyone will be able to check at the freight'ers website that the parcel has really been sent and vote the transaction to A's favor. If the weight of the package seem illocigal, like a laser printer that weights 0,1 g, of course people will vote the transaction to B's favor.