Since 1973, the General Social Survey (GSS) has asked Americans the following question: "Do you think it will be best for the future of this country if we take an active part in world affairs, or if we stay out of world affairs?" Now, granted this is not an ideal measure of interventionism, but let's see where it takes us, anyway. GSS people were lame and didn't ask the question between 1995 and 2005--only sociologists would take five years to get around to asking an important post-9/11 question.
Support for involvement in world affairs has never been lower--39.2% of Americans in 2006 said we should stay out. We have to go back to 1982 to find a similar number (perhaps Americans were reacting to Iran during that period).
If you're a paleo like me, that's good news, but the bad news is that we are still a minority. Other surveys show that a clear majority of Americans want the troops to come home soon from Iraq, but that doesn't mean that most people want us to pull back the empire in general.
Iraq is a total mess, and yet I am amazed over how many moderates and conservatives have embraced John 'Make it a Hunderd' McCain. In a discussion the other day with a friend who is a huge McCain supporter, I asked him what do I get for the $9000 I have to pay in taxes for Iraq, and why do we need all these bases all over the planet? He answered, "Did you watch Spiderman?" I nodded yes, and he spoke as if quoting the Bible, "With great power, comes great responsibility."
So, my prediction is that the person who will win over our current generation of voters in November is the candidate who quotes the most comic books.