There has been a flurry of activity around this choice in the blogosphere, as it were, with some people wondering if this is John McCain's Harriet Myers moment and others proclaiming it to be bold. I agree most with Tyler Cowen:
[These] commentators are falling into The Trap. Most American voters do not themselves know much detail about foreign affairs and their vision of an experienced leader does not require such knowledge. Was it demanded from Reagan? Doesn't everyone agree that Cheney and Rumsfeld knew plenty? Rightly or wrongly, many American voters will view Palin's stint as mayor of small town, her background in sports, her role in a beauty contest (yes), her trials raising teenage children, and her decision to stick with her priinciples and have a Downs Syndrome baby as all very valuable and relevant forms of experience.
The old cliche that voters tend to vote for the person they'd like to have a beer with rather than the person that's best qualified may indeed be the case here.