To defeat terrorism, specifically the most impressive attacks, you must cut off the terrorists' sources of funds. Mission accomplished. In fact, thanks to the mortgage meltdown, we cut off everyone's funding.
I heard on 60 Minutes that Saudi Arabia needs oil to be at $55 a barrel just to pay the bills. With oil near $40 a barrel they are in trouble. I assume other oil producing countries are in the same leaky boat.
When oil prices were high, most people assumed prices would stay high. So oil rich countries started investing and spending like crazy, getting their citizens and friends addicted to higher standards of living. When those countries need to pull back on that spending, where do you think they will cut first? I think it will be hard to fund terrorists when you can't afford to pay the garbage man. And keep in mind that a successful terrorist attack on U.S. financial infrastructure could further lower the demand for oil.
I'm overstating the case, as I like to do, but I have to think it is becoming clear to everyone that a frail U.S. economy is bad news for everyone who would prefer driving a car over riding a camel.
On a related note, you haven't heard much bravado from Chavez and Putin lately.