Why, exactly, is it wrong for MoveOn to refer to General Petraeus as "General Betray-us", but it is O.K. for Ted Nugent to threaten violence against Democratic candidates for president?
MoveOn took out a newspaper ad that criticized U.S. policy in Iraq and argued its case against the war in print. That resulted in a U.S. Senate resolution criticizing the organization. Ted Nugent, a proud Republican, can publicly threaten people and the Senate cannot be bothered to condemn him.
There are two standards for free speech in this country: If one is a right-winger, one can say things that would get a left-winger arrested (the Secret Service frowns on threats to the people whom it protects), but if one is a left-winger, one gets condemned as a traitor, or tasered.