In case anyone's wondering why Bush retracted the pardon of his contributor's son, it's not because he had an attack of conscience or even because it looks bad politically to pardon a mortgage scammer.
It's sadly because the pardon would have made it harder for the Republicans to tank Eric Holder's nomination on the basis of the Marc Rich pardon. One of their most substantial hissy fits was that that Holder signed off on it when it hadn't gone through proper channels (something that was not unprecedented then either.) It turns out that this Bush pardon was granted under similar circumstances.
Remember, Rove is orchestrating the Holder strategy and he's made clear that the Rich pardon is going to be at the center of it.