Between June 1 and October 18 the dollar price of oil on the New York Mercantile Exchange increased by 37%, while in the same period, the price in Euros had risen by almost 30%. There is clearly a lot more at work here than the weakness of the dollar, at least over the last four months.
So while each of these factors has contributed to the escalation of oil prices since 2003, they don't explain why we suddenly find ourselves staring at the prospect of $100/barrel by Christmas. Instead, I think we have to examine the long-term fundamental trends of the industry, which are currently colliding. Demand continues to grow, driven by strong global economic growth, including many places where consumers are insulated from the true market price of petroleum products. Non-OPEC production can't keep up with this growth, because of the combination of production decline rates, drilling bans, and the lagged effects of the near collapse of the industry in the late 1990s. And that's where OPEC comes into the story.