Maybe the two most common explanations (or myths) about high oil prices are:

1. oil companies are manipulating prices
2. speculators are driving prices up

Of course, these two explanations are satisfying our natural impulse to find scapegoats rather than facing the depressing facts of fossil fuel depletion. Robert Rapier already debunked the first allegation, the second one is much more nebulous and has always troubled me since I got interested in peak oil. Stuart Staniford looked also at this problem (Is Oil in a Price Bubble?) by noting that price were following a clean exponential rise (at least until the beginning of this year) and not an upward quadratic model which has been observed in the real estate bubble. Last year, the Senate Permanent Subcommittee on Investigations has published a report supporting the speculative theory. Yesterday, the Qatari Energy Minister, Abdullah bin Hamad al-Attiyah declared:

"To increase by 500,000 or one million barrels, do you believe today it will bring back the price?" Attiyah asked. "I don't think so," he said, emphasizing his view that the price of oil had become almost wholly decoupled from supplies. Financial players "lost a lot of money on real estate, shares and bonds, and then they jumped to commodities," including oil, Attiyah said.
Herald Tribune