Man, the timing. Check out the article in the latest issue of Vanity Fair:
Todd S. Purdum on Sarah Palin | vanityfair.com
Especially this part:
"A year ago, 80 percent of Alaskans viewed Palin very favorably or somewhat favorably; by this spring, just 55 percent had a positive opinion. All this has given rise to speculation in Alaska that Palin may not run for re-election next year."
And now she's quitting, without even serving out the rest of her term.