The WaPo article notes that some of this is old news, and the timing of the article--connected with the Michael Hayden nomination--is surely a little suspicious. Also worth noting is Power Line’s observation that this report further compromises our efforts to keep track of terrorist communications.
This Volokh Conspiracy post, together with the comments, offers a little insight. And if you read the newspaper articles carefully, it’s not clear that there’s any illegality or much of a threat to anyone’s privacy. In other words, my initial inclination, subject to change, is that much of the sound and fury about this is politically motivated, intended further to wound the Bush Administration. The incidental side effect of this is, I repeat, to give terrorists further information about what we’re doing to track their communications.
Update: A quickie poll suggests that the politics of this issue currrently favors the Bush Administration. Some portion of those polled seem to favor the program, but also approve of public disclosure of it, which defeats the program’s purpose. Oh well.
The Congressional reaction, further detailed here, is predictable. The disclosures will galvanize and mobilize the Democratic base, enable Senators to posture and pontificate during the Hayden confirmation hearings, generate bad press for the Bush Administration, and yet--perhaps--actually help the Republicans overall. Stated another way, if Democrats attempt to exploit this issue, it’s evidence not only that they’re not serious about security policy, but that they’re not capable of making sound political judgments. For more on both these points, see this article.
Update #2: Some of the complex legal issues are canvassed by Orin Kerr and his commenters here, a post I missed when I first wrote about this issue. Suffice it to say that there are plausible arguments on both sides; the issue is whether the Article II executive powers and the AUMF come into play in such a way as to overcome all the other legal subtleties.