See these comments:
"Most Americans have tended to give the Bush-Cheney administration the benefit of the doubt when it comes to its failure to take action in advance of 9/11 to guard against an attack. Hindsight casts a harsh light on mistakes that should have been visible at the time they were made. But now, years later, with the benefit of investigations that have been made public, it is no longer clear that the administration deserves this act of political grace from the American people."
What is he saying?
This is couched in diplomatic language, but the intention is clear. He is not buying the Bushies' excuses for September 11th 2001. He's attributing this lack of trust to the "American people," which polls on 9/11 support. But he is also going out on a political limb and making a value judgment as to whether the Bush regime "deserve" any trust on September 11th issues.
Very few politicians have dared challenge the regime on September 11th. Gore is the exception here, which is notable. These are carefully chosen words that appear in his book The Assault on Reason as well as on the Guardian website and "progressive" US websites.
A lot of very committed peope have been shouting about the regime's "failure to take action in advance of 9/11 to guard against an attack" (as well as during the actual attacks) for a very long time, and yet are routinely attacked for doing so -- sometimes on the very same websites that re-published Gore's article. Well how's that for a bit of hypocrisy?
Back in 2004, Gore touched upon some 9/11 issues in a speech:
"Bush described this rigorous and formal analysis as just guessing. If that's all the respect he has for reports given to him by the CIA, then perhaps it explains why he completely ignored the warning he received on August 6 th, 2001, that bin Laden was determined to attack our country. From all appearances, he never gave a second thought on that report until he finished reading My Pet Goat on September 11 th." 
This is -- if you can believe it -- also diplomatic language, because the other explanation of Bush's actions is too politically unthinkable for him to say out loud. Gore belongs to a political caste that doesn't accuse others of the caste of criminality, or of high treason. It's just not done.
For clarity sake, let's have no mistakes here. The August 6 PDB is NOT the only warning this regime received by a long shot. Bush himself was moved out of his high rise hotel, by his own Secret Service, in Genoa Italy in July 2001 because of a warning of an "Al Qaeda plot" to hijack commercial airliners and "crash them into the summit of industrialized nations." The ignorance excuse ends right there.
Many dozens of warnings were reported by mainstream news organizations. Even CIA head George Tenet and CIA Counterterrorism head Cofer Black warned the administration, every member of the cabinet -- including Bush in Crawford TX  -- of impending and imminent attacks.
Nothing was done about these warnings.
Gore elaborates on similar warnings received during his tenure as Vice President:
"The only warnings of this nature that remotely resembled the one given to George Bush was about the so-called Millenium threats predicted for the end of the year 1999 and less-specific warnings about the Olympics in Atlanta in 1996. In both cases these warnings in the President's Daily Briefing were followed, immediately, the same day - by the beginning of urgent daily meetings in the White House of all of the agencies and offices involved in preparing our nation to prevent the threatened attack." 
I think it's safe to say that Gore smells a rat. Perhaps he can't come right out and say it, but he's leaving clues for others to take up and pursue. He appears on the surface to have accepted some of the excuses put out by the regime, but in other contexts he flatly rebukes them and seeks more investigation.
That is the primary purpose of the 9/11 Truth Movement, to uncover the ugly buried truth that the Bushies have made "classified." Gore is at least to some extent working toward the same ends.