Gold has failed just as often as fiat currencies have. When the Spanish conquered the Americas, the natives were amused that the invaders saw value in such a useless metal, but the amount of new gold that was discovered caused significant inflation back in the old world because Spain was just sitting back, buying everything it needed with its gold, and producing little of value.
Similar things happened when Africa came online as a significant source of gold, it got to the point that gold was no longer a stable representative of value, because anybody could just mine more! So you see lots of movement away from gold throughout the 20th century to something...more stable...fiat currency believe it or not. Countries now have control over their monetary policies, for better or worse, and are not beholden to some arbitrary metal.
Ok, so its more complicated than that, but reading http://en.wikipedia.org/wiki/Gold_standard is quite an experience if you are a goldy.