Funny. I've talked to some blokes from Iran, and they seem pretty stable. A war probably won't happen, if for no other reason than it's an expense neither side really wants to deal with. Oh, there will be talk and threats and blah blah fearmongering from the American media. That's how they make money. Calm and good news doesn't sell. Panic and bad news does. They will do everything they can to hype this fear as far as it will stretch, but wars these days do not start easily. There have been fewer wars in the past 100 years than in the previous hundred, and it's starting to slow down even further. If it came to a nuclear war, the United States would leave Iran a smoking ruin. If it came to a conventional war, Iran's military trying to fight off coalition forces would face a logistical nightmare. If it came to a war of attrition, they'd run out of bullets before we ran out of people.
There is always room for blunders to ruin the war, but Iran has too much to risk, too little to gain, and they know it. So they'll threat. They'll shout. They'll put up a tough facade, because pride demands it. But even if they won the war, they'd have lost almost everything else that matters anyway.
The United States meanwhile, will not willingly fight due to our finances unless provoked. A war might be good for our economy, but ONLY if Congress issued a formal declaration of war, which would reroute American industry to providing for it; it's what brought us out of the Depression after WWII, because winning the war was THE priority, and every level of American industry and society was involved.
But that won't happen. And a "police action" (which is what the war on Terror was) is economically unfeasible.
America can't afford to launch a proactive attack, and Iran can't afford to face a retaliatory strike.
It's lose-lose, and so I don't think it will happen.