Politically speaking, it sort of undermines a large part of the case against Obama: inexperience, lack of credentials, lack of foreign policy and national security know-how.
She has never worked in D.C. so there will be a steep learning curve – and probably a few slip-ups. (Then again, McCain will make sure she has a great staff.)
And then to all those on the Right who have called the Obama candidacy an example of Tokenism, there’s this question: Would Palin would been picked if she were a man?
And the Unknowns:
How will the female thing play? The pro-choice feminists will all hate Palin, but the female Republican base might show up in never-yet-seen numbers. Bitter and disaffected Hillary supporters might vote for her out of spite. Or they might see her as a threat to Hillary in 2012 and decide they don’t want her anywhere near D.C.
(And what about the guys? Will men vote for her because she’s got great legs and is just waaaay better looking than Biden?)
Also, how will she do on the stump? Can she hold her own? Will she make any major gaffes (which will cause the opposition to Shriek and Point at her Inexperience)? Will Biden handle her well or come off looking like a bully when he goes up against her?