You can find the original New York Times articles breaking this story here and here.
One interesting aspect of this story is that it may pit the Executive and Legislative branches of government against each other. Under the United States Constitution, Article II, Section 2, Clause 1, the President is Commander in Chief of the military. In World War II, the President didn't need congressional authorization to tell the military to intercept and monitor German communications. On the other hand, Congress has the power to pass laws, and the Executive branch generally has to follow those laws. Finally, the 4th Amendment prohibits unreasonable searches and seizures. (Intercepting a communication is a type of seizure -- you can seize information just like you could seize a physical letter, a weapon, or contraband.) That amendment also requires search warrants in some cases, but not all (for instance, you don't need a search warrant to conduct a fire inspection of a building, even though that's a kind of search.) Now, after 9/11, Congress passed an Authorization of Military Force, which was sort of an open-ended declaration of war: it told the President to go find whoever did 9/11 and make war on them. So, the question is, can the President use his war powers, as authorized by the Authorization of Military Force, to listen to communications between U.S. citizens and foreign citizens without a search warrant? Conversely, does Congress have the power to pass laws, like the Foreign Intelligence Surveillance Act, to limit the President's actions? And finally, if matters come to a head, will the Supreme Court be willing to get involved in the dispute?
I recently heard a commentator say that the Bush presidency could be remembered as exceptionally good or exceptionally bad. Either he'll be the President who defended us from terrorists and led the Middle East to peace, or the one who plunged the country into unnecessary war. I think the stakes in the game just got higher.