So far, I haven't read of any administration official using FISA as the source of authority or justification for the surveillance reported by the NYT.
From President Bush's presser this morning ...
President BUSH: Now, having suggested this idea, I then, obviously, went to the question, is it legal to do so? I am -- I swore to uphold the laws. Do I have the legal authority to do this? And the answer is, absolutely. As I mentioned in my remarks, the legal authority is derived from the Constitution, as well as the authorization of force by the United States Congress.http://www.whitehouse.gov/news/releases/2005/12/20051219-2.html