It should be noted, for future record, that the President of the United States has just used his power of clemency to sabotage an active criminal investigation into the office of his own Vice President. In some parallel universes, I have heard tell that such a thing was once itself considered corruption, or obstruction. It seems at minimum useful to put a footnote in the history books, somewhere, that such a remarkable thing could happen and still receive not merely praise, but unsheepish celebration among people who pretend nightly to be serious about such things.
I think almost everyone involved sees this as what it almost certainly is: Scooter Libby, loyal to the last, is getting his pardon on the installment plan. There is little advantage — and distinct disadvantage — for Bush to pardon the charges entirely, at the moment, but Bush indeed came through with an impeccably timed effort to ensure Libby faced no actual material consequences from his actions. Facing immediate jail time? Then kill the jail time. All of it, from day one onward. If Libby was in any actual danger of having to pay his $250,000 fine, there seems little doubt he would have seen that part of his sentence commuted as well.
But now Libby is in no imminent danger: problem solved. Bush has neatly and in one action removed any impetus for Libby — or anyone else — to cooperate with government investigators. There is no leverage a prosecutor can use against Libby, in order to gain a plea deal in exchange for information that he has so far refused to provide. Conservative backers have contributed more than five million dollars in a slush fund for Libby's defense, and are eager to help him in his hour of need.