It's possible to make use of the Mt Gox API to immediately (within transfer time) sell all Bitcoins received (or the portion thereof for which USD is needed) for USD after they're received. Anyone too retarded to figure this out shouldn't be running an online business anyway. They should go start one of those stupid convenience stores, with a sticky floor, which doesn't take credit cards for purchases under $5. 
The change in value during that sort of time period ought to be proportional to interchange fees anyway. If they're really worried about volatility they can store some Bitcoin up front and sell it while the transfer is taking place. Thereby allowing more sales to occur as soon as the reserve is replenished and the transfer has gone through.
The change in value during that sort of time period ought to be proportional to interchange fees anyway. If they're really worried about volatility they can store some Bitcoin up front and sell it while the transfer is taking place. Thereby allowing more sales to occur as soon as the reserve is replenished and the transfer has gone through.