But your example illustrates the real issue -- Newsweek should not have printed the story, even if it were true. People were going to die because of the story, not the facts.
This is very true. However, there's a difference between yelling "Fire" in the ol'crowded theater when there actually is a fire, and when there is none. The first could be justified as a sincere attempt to save lives, even if more lives were ultimately lost because of a stampede; the second is clearly just malicious.
That said, I can't imagine any compelling interest for Newsweek to publish the story even if it had been true, since they must have been aware of the consequences of such a story. However, the fact that it was not true, they published it on the vaguest of rumors and that anybody who worked around Gitmo would have known that those rumors could probably be traced back to Islamist propaganda in the first place, makes it at least gross negligence, I would think. But I don't know whether there is actually any way of prosecuting them or suing them; I suspect not.
Still, I think Isikoff should have to go to Afghanistan and apologize, both to the Afghanis and to our military, and Newsweek should have to pay some sort of compensation to the families of the people who were killed. It might make our "news" sources think twice about doing something like this again in the future.
Mass communications are too effective nowadays to let media sources sit around and casually launch rumors as if they were tossing paper airplanes. Something can now go from the desk of a Bush-hater in NY or DC to primitive rioters in the streets of Afghanistan in a matter of hours.