To answer the question, think like a terrorist.
1. Al-Qaida despises western culture, particularly the United States' brand.
2. Osama bin Laden's hatred of the USA is driven by the fact US Military forces are based in his homeland of Saudi Arabia.
3. He knows the only reason the US government backs the royal House of Saud is our dependence on foreign oil. Saudi Arabia is a reliable and efficient producer/exporter of oil.
4. The terrorist's wet dream is to have Israel provoke a war against both the terrorist organizations like Hezbollah and neighboring sovereign states like Egypt, Syria, Jordan, etc.
5. bin Laden wants the American people to answer the question: "What's worth more of a sacrifice....coming to Israel's aid in a war of aggression or assuring the supply of Middle Eastern oil?" bin Laden figures if the game is played on his terms, there will have to be a choice between Israel and oil.
I'm betting the next attack is on some symbolic western target in Saudi Arabia, perhaps the US Embassy, and the audacity of the attack will rally the malcontents to rise up and overthrow the House of Saud. New government in Saudi Arabia, hostile to the United States, forces the US military out of Saudi Arabia. The US is going to have to cut some kind of deal to keep the oil. Maybe higher prices. At the same time, Israel is more vulnerable and may feel pressured to go on the offensive. We will denounce Israel's actions, of course, and set off fierce political debate in Congress between the Israeli lobby and those who fear the shock of manipulation of the oil market.
On the homefront, an occasional biochem or suicide bomb attack keeps everyone jumpy and more focused on internal security. The average American in flyover country won't care about Israel when he's thinking his block is next.
Until the US and it's allies get really serious about this war, it's bin Laden's game to win.