Palin's speech from last night is available at npr.org for download and the quality is good, so you can hear easily things and it's good enough for basic acoustic work. Just a few observations. First, she's got the classic western/northwestern features, things that are found elsewhere, but that many of us associate with the region. The first two examples illustrate that, and the next two are Upper Midwestern patterns that people have commented on, including on ads-l.
- Low back merger (aka cot/caught merger). She talks about 'sons and daughters' and the
/au/ there is a low vowel. Tense/lax vowel merger before coda /l/, what's often exemplified with fill/feel being/becoming homophonous. Her long or tense mid vowels, /e:/ and /o:/, don't look as monophthongal as they seem to sound to a lot of folks, including me at some points. This is often identified specifically with the whole 'Fargo' thing. She often has final devoicing or final fortition, including on -s. Acoustically, it's sometimes even more striking than what we find with Wisconsin speakers we've looked at, and that's saying something. The phrase below is "sons and daughters going". (You only get the beginning of 'going' here.) The 'daughters' has a really devoiced -s on there.
'Sons' is presumably 'passively voiced' due to the following vowel.
But the big question is of course what she sounds like and why. Mr. Verb has already hinted that you get big variability in situations of koine or new dialect formation. In mid-20th c. recordings of Wisconsin speakers, the accents sound all over the map to me, while contemporary recordings from the same areas scream Wisconsin, even specifically eastern or southeastern or western Wisconsin. That is, the Wisconsin accent we know now is very recent, and Wisconsin's (European) settlement is far older than Alaska's.
I don't know the historical demographics of Wasilla, but if the percentage of newcomers is high enough, it could well be that she grew up among those folks, and ended up with an accent that sounds like a thousand or so miles away.