Dollars Vs. Euros the Winner Gets the Oil

The Real Reasons for the Upcoming War in Iraq: A Macroeconomic and Geostrategic Analysis of the Unspoken Truth, by W. Clark
is a fascinating document. No idea how much of it is true, but it sounds like its potentially on point. And if it is its scary.

Key underlying idea is that oil is currently bought and sold using dollars exclusively. Iraq recently switched to a Euro standard and OPEC is thinking about it as well. If that switch happens it will result in a huge drop and destabilization of the dollar, fscking up the US economy majorly. Need to investigate more, anyone know how true this might be?

+++ Update +++
Paul Krugman has rebuted this rumor pretty strongly. I'm inclined to believe him.