I don't follow Alaskan politics nearly as closely as my smart Alaskan friend (obviously), but I'd add one caveat to his sharp enumeration of Palin's political gifts.
Apart from infancy and college, Palin has spent essentially her entire life in Alaska, which really is like another country in many ways. (I've visited a few times and even co-owned some land there.) She's been an elected official for well over a decade and has clearly been preparing herself for higher office in the state for some time--running unsuccessfully for lieutenant governor in 2002, for instance. She knows the issues in the state well, and got herself close to many of the key power brokers (Murkawski considered bequeathing his Senate seat to her, she served as a director of Ted Stevens's 527, etc.).
None of these things, as far as I can tell, is true of her current bid for national office. There's very little evidence that she's given much thought to the national economy, foreign policy, or a host of other issues she'll be expected to be fluent in. She doesn't know many of the pundits or power brokers in Washington and, worse, they don't know her--so few of them will have a personal investment in sticking their necks out for her if things go further south. However formidable her political skills may be, in Alaska she had also laid substantial groundwork for her quick ascent. Outside of Alaska, not so much.
Will it make a difference? Perhaps not. In any case, I agree with my friend that it'd be foolhardy to underestimate her.