EJ Dionne's column today strikes me as pretty silly. A McCain/Jeb ticket, though probably attractive to a few folks out there, isn't really worth 800 words gaming it out. Not in a world where, you know, there are real things that are actually happening. And conceptual critique aside, Jeb Bush doesn't lift McCain's overriding weakness: the primary. If McCain can get the nomination, the election will be run on his terms, he'll not need a Bush to pull it out. If he pulls out the primary, expect Hagel or Lindsey Graham to be joining him on that stage, not Jeb. I guess Dionne might be imagining a scenario where Jeb is announced as his Veep pick before the caucuses, but such an obvious attempt by the Bush family to stack this election in advance would look too dynastic, too hungry. It'd create a deep and quick backlash. Remember the criticism after Gore's endorsement? Imagine it times a thousand.
Plus, if Jeb does decide to join the ticket, Democrats always have one more card they can play. The constitution says nothing about a two term president running in the Veep slot, so McCain/Bush better brace themselves for Clinton/Clinton.
Update: Never mind that last part, I apparently know nothing about the 12th amendment.