Timothy C. May says:
I suspect that verification that a physical quantity of gold is held is much less important than that depositors can freely get back their deposits. I suppose this means I don't see a real need for gold-backed money. (At the national monetary system level, hard assets may be a good idea, but at Joe's Bank I don't see any rationale for it having, say, 132.74 kilos of gold in its vaults!)
Although this is not the right place for discussing this topic, I can suggest a reading of "The Theory Of Free Banking" by George Selgin, which is an excellent economic treatise on why a bank might want to hold a particular physical commodity as backing for bank issued notes instead of relying on a central banking system. The book is an expansion of Selgin's PhD thesis at NYU -- its pretty good. Even barring this, however, a protocol to determine if claimed deposits correspond with what depositors think their deposits are, i.e. an audit protocol, has many uses and would be valuable. Its a genuinely good problem. Perry