I'd just like to point out something that seems obvious to me.  Any central exchange/business selling for bitcoins/private party that reneges on debt, is an actual person, who already lives in a meatspace jurisdiction.  Bitcoin transactions are simply viewed as barter under normal state laws, and there are already bankruptcy systems and court systems.  If we set up a system for the bitcoin community, it is not enforceable without coercion, since we do not have a monopoly on force in any meatspace jurisdiction, attempting to enforce community rules will likely involve things that are technically illegal, and limit acceptance of bitcoin as a whole.  This is all very nice to try to make a working anarchocapitalist platform, but if you want mainstream acceptance we can't set up our own system of laws and courts, real world businesses will simply not participate in such a thing.  It is better to just view this as a parallel market where, while normal laws apply, they are very difficult to enforce, and exercise due caution because of this.