The U.S. Court of Appeals for the District of Columbia Circuit by a 2-1 vote (Rogers and Tatel, Henderson dissenting) has overturned the conspiracy conviction on Article III grounds.
Steve will be posting much more shortly on the three opinions in the case. [UPDATE: Read all about it!] But for now, this is the most important point: This decision does not disempower the government at all in terms of its ability to prosecute crimes committed by enemy forces: Domestic-law offenses can be — and successfully have been — prosecuted in Article III courts, with juries and judges who have tenure and salary protections; whereas violations of the international laws of war, such as those alleged in the 9/11 case, can also be tried in military commissions.