The implicit premise in the Republican attacks on Speaker Pelosi is that if she sincerely opposed torture, she had a duty to publicize the classified information she received in briefings. This point seems to have been lost on the traditional media, which generally have been allowing the Republicans to equate non-disclosure of classified information with support for torture.
The only incident that I recall involving a member of Congress publicizing classified information due to its importance to the public is Speaker Jim Wright's disclosure regarding covert CIA support for opposition groups in Nicaragua. At that time, the traditional media focused almost exclusively on the question of whether Wright should be punished for making the disclosure. Wright did not succeed in focusing public attention on the Reagan Administration's subversion of Nicaraguan democracy.
What if Pelosi had gone public in 2002 or 2003? Clearly, she would have placed herself at serious risk of criminal prosecution. Republicans would have become even more vitriolic in seeking to characterize the Democratic Party as the party of treason. The Cheney Administration would have provided disinformation to place the torture program in an innocent light, and Pelosi would have had little if any access to evidence to contradict the Administration's claims. Does anyone who remembers the political climate in 2002-2003 think that Pelosi's disclosure of the very limited information available to her would have mobilized public opinion against torture to such an extent that the Bush Administration would have been compelled to stop?
I have no right to be surprised by the utter cynicism of the GOP attacks on Pelosi. It just seems particularly appalling to me because it involves such a grave matter of conscience that until recent years would have been beyond the pale of partisan dispute.
Update: As noted in the comments below, Sen. Gravel's disclosure of the Pentagon Papers was found to be protected by the Constitution's speech or debate clause.