I am not sure there is a simple explanation for what's happening with crude oil prices. As with any unprecedented run-up in price on anything from Enron stock to tulip futures, there is always a mix of greed, speculation, widespread fear or eagerness, supply issues, etc. Please note the price of air and water have not radically altered because generally we believe them to be in plentiful supply.
Finally, there's been some exploration of the financial rigging behind the full sails that carry the ship of oil-price into ever new waters. Low and behold, there's been massive de-regulation in the US, allowing ever more wealthy players to get into the crude oil futures speculation business.
Fantastic short-term gains to be had right now. Long-term the high oil price is driving more and more investment into alternative energy tech, thereby possibly hastening the decline of the oil industry's economic stranglehold on the planet. You have to savor the ironies where you find them.