Er, point of order. Enron was on the first of several frauds that took place during the 90s that weren't detected until early 2001. At that Enron was a relatively minor bankruptcy compared to several others related to corporate frauds from the same period. For example, the AICPA estimates that Worldcom's fraud was 15 times the size as Enron's ($9 billion to $600 million). For that matter Enron wasn't really an oil company, they were energy traders, a busines that grew out of their experience running pipelines. I don't remember them ever being a major player in the production end of things. Speculators are having an impact on current prices, but hey, Enron's not really part of it. Sorry for the diversion.

According to NPR (and the Economist) a couple of weeks ago, $8-10 per bbl of the current price was due to a risk premium founded on concerns about the reliability of supply, not the quantity. Economic growth in the US and China has increased demand, but not any where near what would drive prices to above $40/bbl. Saudia Arabia's announce intention to increase demand would normally have had a calming effect and driven prices down. It's clear that the attacks in Saudia Arabia were timed to upset that and keep prices high. The way the Saudis dealt with the attacks was apparently reassuring enough to cause a major decline in prices (at least going into the weekend, I haven't looked since Friday).

US refining capacity is also a part of the problem with gasoline prices. US capacity has declined 2% over the last 20 years all the while demand has grow considerably. We actually closed many older, less efficient refineries over that period; only significant improvements in production have kept us anywhere near the levels of production we had in the 80s.