I've heard a number of people (from far-left peaceniks to prominent libertarians -- though those two groups are not as far apart as you might think) say that America brought these terrorist attacks on itself. Many reasons are cited, from discomfort over Hollywood "culture" (I use the term advisedly) to frustration over the foreign policies of the U.S. government. Now I'm no fan of the major industries in Hollywood or Washington D.C. (neither of which is to be confused with the people living in America), but the simple fact is that culpability for these attacks lies squarely with the perpetrators. The U.S. government has meddled (wrongly, IMHO) in the affairs of nations across the globe, and has supported unfree governments in nations as diverse as Chile, Thailand, Mexico, Korea, and South Africa (to name just a few), not just in the Middle East. Do we see terrorists from these nations making war on America and Western civilization? Why is it that U.S. government foreign policy or Hollywood culture incites to acts of violence only groups (I'm tempted to call them tribes) on the radical fringe of Islam, and not also Buddhists and Taoists and Catholics and many other religions and cultures? I think I need to do some research on Islam....
On a related note, I must say it irks me when people talk about the "tragic events" of September 11th. This was not a tragedy, in the Aristotelian sense or any other. This was an atrocity.