McCain is making a play for the PUMAs with this ad, as well as the new print McCain/Hillary leaflet thats getting passed around mostly in PA. - It seems most of the remaining undecideds are heavily Clinton-supporting Dems who hate Bush, but REALLY hate Obama, and are conflicted over supporting a platform, or a party.
In short, Its another "I am not Bush" advertisement.
Thankfully, the 527s are bringing out the heavy artillery for the rest of the election.