No surprise that the leak came from ABC-TV, a news network which notoriously upholds its national anchorpersons, like Peter Jennings, Ted Koppel, Martin Bashir, Cynthia McFadden and Terry Moran with greater esteem than it does the safety of the citizens of the United States. From the excellent NY Sun:
Al Qaeda's Internet communications system has suddenly gone dark to American intelligence after the leak of Osama bin Laden's September 11 speech inadvertently disclosed the fact that we had penetrated the enemy's system.
The intelligence blunder started with what appeared at the time as an American intelligence victory, namely that the federal government had intercepted, a full four days before it was to be aired, a video of Osama bin Laden's first appearance in three years in a video address marking the sixth anniversary of the attacks of September 11, 2001. On the morning of September 7, the Web site of ABC News posted excerpts from the speech.
But the disclosure from ABC and later other news organizations tipped off Qaeda's internal security division that the organization's Internet communications system, known among American intelligence analysts as Obelisk, was compromised. This network of Web sites serves not only as the distribution system for the videos produced by Al Qaeda's production company, As-Sahab, but also as the equivalent of a corporate intranet, dealing with such mundane matters as expense reporting and clerical memos to mid- and lower-level Qaeda operatives throughout the world.