The beauty of being a criminal in a well-organized criminal syndicate is that you know you're protected by the people above you. Sure, they might hang you out there to take a rap or two, but they'll do what they can to make sure you're not too put upon and that you're justly rewarded for your sacrifice to the family.
And so, Scooter Libby avoided jail time when the titular head of the executive branch exercised his Constitutional right to pardon or commute convicted criminals. Every President does it, although generally not in such an obviously partisan and blatantly uncalled for way. Usually a President waits until the end of his term before turning to the business of pardons, and then the pardons are doled out to relatively obscure figures, perhaps tertiary attractions to the main show, but Bush went straight to the payback for Libby sitting there and taking it on the chin for the most corrupt administration since Richard Nixon's.
Speaking of which, the Libby commutation is perhaps even filthier than Ford's pardon of Richard Nixon for "any crimes he may have committed against the United States while President" -- about as broad a whitewashing as you can imagine.
Bonus points for anyone who can identify the origin of my post's title.