Maybe something can be learned from
http://www.playerauctions.com?
They are mostly known for allowing people to buy money in online games, but they also opened a bitcoin exchange. Bitcoins are able to be bought with a credit card, and Playerauctions guarantee the payment of sellers.
Trading video game items and currency is about as nonreversible as bitcoins are, and those markets seem to be doing fine.
This is exactly what i was wondering. Why people are so scared about reversing transactions when credit cards are used around the globe and no one is going to bankrupt because of that. Why only bitcoin sales would have to suffer?