In response to Rosy the Bull, I have to say I'm not so pessimistic. I heard
similar dire warnings about how the US economy would collapse at $3 a gallon
gas, and it didn't happen. A great many countries in Europe and Asia, with
smaller economies than ours, are paying over $6 a gallon now, which as a percentage
of per capita income is five to ten times what we're paying.
As to the comments on nuclear attacks, those are inaccurate. Depleted Uranium is barely radioactive, and its danger is as a colloidal heavy metal toxin. The dangerous radionuclides from nuclear blasts are dangerous because of their short half life. It takes days for most to reach safe levels, months for a few. Even most of the area around Chernobyl is now repopulated, and that was a far more toxic contamination than most nuclear weapons. (The Ukraine insists it's not safe, despite people living there and GUIDED TOURS, because they get aid money from fuzzy-minded anti-nuke types.) Almost all nuclear weapons these days are designed for efficiency, and the "dumb" ones are still a triple stage fission trigger with a tritium squirt to generate enough extra neutrons for the remaining fissionables to be as thoroughly used as possible. The Hiroshima and Nagasaki bombs were 1.4% and 14% energy efficient. Modern fusion boosted weapons are up to 40% efficient. It's normally the case that the radius of total destruction exceeds the radius of the radiation.
Even with crude weapons--there are people living at ground zero in both Hiroshima and Nagasaki today, and were there within a few months of the attacks. The fear of contamination lasting "lifetimes" is groundless.
While any disruption of oil will affect the world market, whether or not we get oil from Iran (Which at present we mostly don't), I'm more concerned about the long term effects of industrializing India and China. Their populations are going to need massive amounts of resources, and no amount of politicking will reduce the effect. High fuel prices are the way of the future, and they are painful. But I don't believe they're going to cause a collapse.