Variations on this theory have been kicking around for quite a while, yet I rarely see this discussed. Maybe 'cause it's easier to talk about apocryphal meeting of "el kayda" and Saddam.
http://www.thirdworldtraveler.com/Iraq/Iraq_dollar_vs_euro.html
Basically, Iraq was threatening to switch to the Euro as the currency of choice for oil purchases, instead of the dollar, which would pretty much pull the rug out from under the US economic house of cards.