Apparently it is no longer required in quotes printed by conservative columnists, just as it is not required for videos ran by conservative bloggers (let alone for them to be taken seriously by the administration).
Of course conservatives in the media or elected office attacking Democrats or progressives through an out-of-context-to-the-point-of-falsification quote is not new. Only recently, the targets picked by the right have been so absurd that they have fallen apart within themselves. But it’s not any different than finding a single user-submitted video out of tens of thousands and claiming that MoveOn ran ads comparing Bush to Hitler. Nor is it any different from the massive promotion of a couple of numb skulls who claim to be Black Panthers who tried to block voting at a predominantly black polling place on election day in 2008 (let alone then blaming the Obama administration for the Bush administration choosing not to prosecute them). Nor is it different from nut picking a crazed commenter on Daily Kos or Huffington Post who attacked Joe Lieberman along anti-Semitic lines and claiming that Ned Lamont’s supporters were all anti-Semitic.
Taking quotes out of context or finding non-representative individuals and promoting their views as representative of an entire political campaign or party is stock in trade for the conservative movement.
The only remarkable thing about the Breitbart/Sherrod and Zuckerman/Obama instances of missing context is that they are being called out as the dishonest smears that they are.