An Unlikely Report

With the release today of the National Intelligence Estimate, the big news, of course, is that the NIE judged "with high confidence that in fall 2003, Tehran halted its nuclear weapons program; we also assess with moderate-to-high confidence that Tehran at a minimum is keeping open the option to develop nuclear weapons."
This assessment is close on the heels (October, 2007) of President Bush's comments that "if you're interested in avoiding World War III, it seems like you ought to be interested in preventing them (Iran) from having the knowledge necessary to make a nuclear weapon." (It's noteworthy that Bush didn't cite Iran's having a nuclear weapon as the threat--rather, the threat was their "having the knowledge" to begin with.)
But why was the intelligence estimate released in the first place, particularly since it runs counter to what the White House has been saying? The Director of National Intelligence, Mike McConnell, had earlier said that he would not release the findings since doing so might reveal U.S. intelligence gathering methods to Iran.
Today, however, the Prinicpal Deputy Director of National Intelligence, Donald Kerr, said in a statement that "the decision to release an unclassified version of the Key Judgments of this NIE was made when it was determined that doing so was in the interest of our nation’s security."
To say all of this is a rapid about face is an understatement. What changed regarding "the interest of our nation's security"? Why does the report's release no longer run the risk of revealing to Iran American intelligence methods? From what direction did pressure come (if it did all all) to release this report? Could it be that Defense Secretary Robert Gates--who said this summer that "it would be a strategic calamity to attack Iran at this time"--has more sway than meets the eye?
Whatever the answers to these and a multitude of other questions might be, it isn't often, as the NY Times puts it, that "a single intelligence report [has] so completely, so suddenly, and so surprisingly altered a foreign policy debate here [in Washington D.C.]."