In our continuing discussion of what money is (and are bitcoins money) resident guru Lloyd McAulay weighs in with these thoughts:

When a government prints money to the point where we can not rely on it, then the “money” no longer performs the money function and those affected find another money to use as much as possible (USDs or Zimbabwean dollars  in Zimbabwe and Euros in Greece). Those affected might forego the convenience of paper and use gold as the medium of exchange.
If one is willing to accept the assurance of the Bitcoins program, then Bitcoins does function as money. If not, then not.  Bitcoins are not yet money for me.

Most governments will replace worn out or defaced money. What happens if something goes wrong with Bitcoins? Can something go wrong?

Attached Empirical Measures in the Federal Reserve an analysis of money.