Noam Scheiber has a point:
The reason Palin scares me has more to do with mechanics than demographics: Palin is such a sensation, and draws such large crowds, that anything she says–particularly attacks on Obama–immediately become part of the campaign conversation. On the other hand, both because she has a knack for delivering barbs with a smile, and because voters don’t quite see her as presidential material, McCain suffers less blowback than he would if a more traditional running mate were saying the same things. Simply put, Palin has a much bigger megaphone than traditional running mates, but gets held to a lower standard.
Conservatives have been saying the same thing about Barack Obama for two years. (Except he doesn’t really ever smile.)