Most importantly, as to the McCain Amendment, which would categorically prohibit cruel, inhuman and degrading treatment of detainees by all U.S. personnel, anywhere in the world, the President wrote:

The executive branch shall construe Title X in Division A of the Act, relating to detainees, in a manner consistent with the constitutional authority of the President to supervise the unitary executive branch and as Commander in Chief and consistent with the constitutional limitations on the judicial power, which will assist in achieving the shared objective of the Congress and the President, evidenced in Title X, of protecting the American people from further terrorist attacks.

Translation: I reserve the constitutional right to waterboard when it will "assist" in protecting the American people from terrorist attacks. [UPDATE: Or, as Matthew Franck eagerly puts it over at the National Review, "the signing statement . . . conveys the good news that the president is not taking the McCain amendment lying down."]

Marty also reprints the complete language of the McCain and Graham Amendments as they appear as Title X of Division A of the Appropriations Act.

Here's some TalkLeft background on how the McCain Amendment evolved into into an empty promise. I don't expect McCain to do anything about it either.