A vent. I think you can argue that the perjury issue was incidental to the original crime. You can even argue that there was no crime. But you cannot argue that Libby's testimony was not perjury, unless you claim to know more than the jury; or that premeditated perjury by a leading figure in the government is not something the legal system has a duty to punish clearly. The sentence was in part demonstrative - of the fundamental issue at stake, i.e. whether the agents of the executive branch are above the law. The commutation sends an equally powerful message. The president believes his judgment on these matters is worth more than a jury's. That monarchical prerogative is in part what the American revolution was designed to abolish. And now it has come full circle.
Marty is a great friend. I have no doubt he is sincere in defending Libby. I have no reason to doubt that Libby is a very nice man, for a perjurer and a smear artist for the powerful. But the law must always count for more than mere friendship. Libby broke the law and undermined the judicial system; and Bush's commutation of the sentence is a clear declaration that the rule of law ends at the administration's edge. Thousands of other perjured felons could get a commutation, but they're not friends with George W. Bush and Marty Peretz. And so they have no chance. The bottom line for Americans is this: George Bush's friends do not go to jail. Your friends do.
This is a very simple matter. Either Libby is subject to the rule of law or not. Bush's action is constitutionally solid but morally and politically indefensible - an act of arrogance born of permanent privilege that still, somehow, even after all these years, manages to shock.