The networks move money from one account to another, and then, with normal money, the receiver can withdraw the funds from the account and spend it anywhere. If it is later discovered that there has been fraud somewhere, it's usually too late to do anything about the money. It's long gone. Which is why security matters. When the money's gone there nothing left to do but argue about who takes the loss - and it isn't likely to be the lawyers.
Local money can obviously use the same systems.
But since the money in those networks cannot be drawn out, but must be spent inside the community of those using that particular system, any fraud can easily be reversed. The first virtual money systems are likely to appear on the internet very soon. The first significant applications will probably be business to business networks within geographic trading areas. These will be strongly supported by the growing interest amongst business in using internet in general and World Wide Web in particular for advertising, ordering and invoicing. Tax and the authorities.