It's not clear. Although ABC's Rick Klein reported last night that Nancy Pelosi and other Democrats were briefed on the torture of Abu Zubayda in September of 2002, the month after he was tortured, Greg Sargent now reports that the CIA's own documentation of the briefing is very vague, relying on the “best recollections” of those present at the briefing. Which means at this point it's not clear what they knew.
Conservatives are portraying this as a sort of "trump card" because they believe Democrats' complicity in the Bush administration's torture policy might derail investigations. This is another example of the strange moral relativism of torture defenders: if crimes ultimately aren't prosecuted for political reasons, that means there was no torture and no crime. That's really not the case. The United States tortured prisoners in its custody, and torture is a crime. Our failing to account for it in some manner gives license to every dictator and torture regime on the planet to treat their citizens, and even Americans in their custody, with the same cruelty that we treated suspected terrorists.
-- A. Serwer