Please note: many if by no means all Islamic jurists consider fiat money to be "haraam" if an alternative exists. The goldbug thesis is that an alternative does exist. The "gold-for-gold" section found in the Hadith and most Islamic financiers strongly promote the notion that the weight of gold should be and even is an economic constant.
Also, interestingly, Islamic law favors full-reserve banking.
Why I Got Gold Wrong [View article]
Also, interestingly, Islamic law favors full-reserve banking.