The 575-page report from the 9/11 Commission was released earlier today. You can read the 9/11 Commission Report in it's entirety here.
According to the report, some of the failings of U.S. intelligence and domestic security are that the FBI was not set up to collect intelligence domestically, the intelligence agencies failed to share information, they missed opportunities to possibly prevent the attack, and they failed in "connecting the dots" in the intelligence community.
The final document reportedly illustrates 10 missed opportunities by both the Dubya and Clinton administrations to halt the suicide hijacking plot, six of which are attributed to the Bush administration, four to the Clinton administration.
If I go 0 for 10 in slo-pitch, I have one hell of a restless night. Dubya and Clinton went 0 for 10 and 3025 lost their lives. Almost three years later, it's still hard to imagine.