Pajamas Media has a roundup of blog discussions, pro and con, on the subject of whether the President had the authority to conduct wiretaps, one end of which involves a US person, without a court order. However the legal arguments play out, a slightly different question already has a definite answer: the President does not, apparently, have the reliable ability to conduct surveillance of the enemy without the fact being revealed in the New York Times.—
The Belmont Club: The tightrope
Wretchard mentions the Medal of Honor citation of CAPT John P Cromwell. Useful reading. Especially for the Times' sources.