McCain's surprise choice would have made more sense had the reconciliation with Hillary Clinton--and, one presumes, many of the women holding out on Obama--not been so complete this past week. But clearly the McCain team thinks that fissure is still real and can be torn back open. It certainly won't be hard getting the media to play along.

The short-term news impact--and thus intrusion on the high of Obama's acceptance speech--will be far buzzier than, say, a Tim Pawlenty-though one certainly hopes there was much more to the choice than that.

A major downside is that, given her inexperience--an Obama campaign statement declares that "[t]oday, John McCain put the former mayor of a town of 9,000 with zero foreign policy experience a heartbeat away from the presidency"--there's going to be quite a lot of talk abut McCain's health and actuarial life tables. And it will be fun to watch her debate a 30-year Senate veteran, that's for sure.