http://www.spectrum.ieee.org/jun08/6274
This article talks about the technological singularity that some are expecting as similar to the industrial revolution as a stage in human progress. It mentions that no one thing was responsible for the industrial revolution. Perhaps fiat currency was one of the many necessary things that came as part of the change, just as a further progress will demand an entirely new form of currency again soon.
Maybe fiat can only work in an era of small governments and a relatively slow pace of commerce. In a time of globalisation, increasing powerful money issuers, increasing velocity something new may be necessary, technologically advanced enough to reflect the era that demands it.
How about bank notes made of nanobots? This way currency might not only represent work, but could also do the work - the ultimate guarantee of value. A chest of drawers would cost ten pounds, because a ten pound note would actually build you a chest of drawers.