CNN is apparently using that as proof the "X" was an honest mistake. However, it neither proves nor disproves anything. The media will drop it and make it into a non-event, though CNN's done image editing of the Bush administration before.
Sounds like they had their preview monitor hooked up wrong, but why only for Cheney's speech?
I can see someone in the control room having a goof with it when he realized that the X ended up right over Cheney's face, and he didn't realize that it was going to go live.
I hope that person is serving coffee to the chyron ops after this.