i was wondering if there are any exchanges which trade centralized virtual currencies for decentralized virtual currencies. for example, air miles for bitcoin or vice versa. my thinking is that this might externalize the charge-back problem inherent with fiat currency - ie the problem where someone sends fiat to the exchange, in return for bitcoin, then claims the money was stolen or the transaction was somehow illegitimate, and the bank takes the money back off the exchange leaving the user having paid nothing for their bitcoins.

of course i'm thinking that the centralized virtual currency also would not have chargebacks, but this may not be the case? here are some examples:

• linden dollars from second life
• amazon coins
• air miles
• gift voucher codes