9/11: Air traffic control audio released

Some of these tapes have been released before — but others have never been heard.

They were dug out of the 9/11 Commission’s archive by Rutgers University law school.
For the first time you can hear the entire exchanges between ground control, pilots and the military during the chaos of the 9/11 hijackings.
According to The New York Times, which first reported on the release of these recordings, one key tape remains unreleased: the recording from the last half hour in the cockpit of United Flight 93 that crashed in Pennsylvania instead of its intended target in Washington, DC.

It was played at the trial for one of the plotters, but the families of the passengers who took on the hijackers requested the audio not be made public.
Video: Three of the recordings:

Links: The New York Times – The 9/11 Tapes: The Story in the Air
The New York Times – Newly Published Audio Provides Real-Time View of 9/11 Attacks