I don't think they'd be quite as hard to displace as people assume either. I've not spent very long looking at MtGox but I'm sure that all the usual tricks that

I don't think they'd be quite as hard to displace as people assume either. I've not spent very long looking at MtGox but I'm sure that all the usual tricks that real-world exchanges use to boost usage would work against MtGox as well - offering tighter spreads, lower transaction fees, encouraging market makers with incentives such as refunded fees as long as they're covering the market for a certain portion of the month, etc.