I'll be honest. I have very little patience with the current trend of hand wringing that goes on, of obsessive self analysis about "why they hate us so much". I guess its a cultural thing. I am not American. I don't understand it. - Just do your thing and don't worry about it. This is not a popularity contest. Its about looking after one's (read: Country's) self interest. That's what everyone else does. That's what USA does too.
My favorite historian has his own take on the issue. Check it out here.
My take on "Anti Americanism" is that it's always been there, and it will always be there. The events of 9/11 have just driven home the point: (well actually several points)
1. That people hate the USA,
2. That people secretly hope to see the USA fail/ be humiliated in some way,
3. That the USA is vulnerable to attack, and will continue to be vulnerable to attack.
But here's the thing that I think many forget: Life is good here. It is a hell of a lot better than in many many parts of the world. When immigrants both legal and illegal stop clamoring to come here- then we can start getting worried.