The biggest strike against her, of course, is her utter lack of foreign policy experience. Although I suppose that if McCain continues to make the argument that Putin wants "to restore the old Russian empire," then he can also argue that Palin has been playing a key national security role by preventing a Russian expeditionary force from coming across the Bering Strait.
One thing I wouldn't discount is the weird current appeal of Alaska. Thanks to reality TV shows like the Deadliest Catch and Ice Road Truckers*, Seward's Folly is enjoying a popular culture renaissance of sorts. (The Discovery Channel evidently aired an entire Alaska Week; all Delaware has is an old TNR cover story calling for its abolition.) I'd imagine the McCain campaign will treat us to lots of images of Palin and her family on snow mobiles or whatever. The fact that you'd rather go Alaskan king crab fishing with Palin instead of Obama is, of course, a dumb reason to vote Republican, but people have been known to cast their votes for very dumb reasons before.
*--Ice Road Truckers is actually filmed in Canada, but until writing this post, I'd assumed it was shot in Alaska; I'd imagine a lot of other people make the same mistake. All that frozen tundra looks alike.