I think KurkiKhan is making way too much of this. As I've already covered, pardons (which this isn't) have a time-honored tradition and are entirely legal under the Constitution- for good or ill.

As a political move, it's actually a good one- which is a refreshing change from the Bush White House. He had nothing to lose by doing so, and stood to gain a little by doing it. People who hate Bush will still hate Bush- nothing is going to change that. The people who don't care about "Plamegate" still won't care- which is probably the largest group. And those that thought Libby was railroaded by Fitzgerald, will be undoubtedly pleased by this.