I think this thesis of this piece, that "Sarah Palin's happiness is what really irks liberals," is only partly true. Her detractors can present much more solid reasons for finding her an objectionable political personality. But there's probably a little something to it. For an awful lot of people who are on what I call the cultural left, which is more concerned with criticizing traditional social institutions than with ordinary politics, and which overlaps but isn't identical with the political left, a decent and reasonably happy middle-class American family isn't really supposed to exist. The American family is the family of American Beauty: disturbed, repressive, disintegrating, outwardly pleasant (maybe) but rotten with dark secrets. I can imagine that Palin's upbeat straightforward middle-class-ness is an extra twist of the knife to those who already detest her.
It's the counterpart of conservatives vs. Hilary Clinton: we didn't like her politics, of course, but it was her Nurse Rached vibe that really drove us crazy.
Of course she annoys and worries a lot of conservatives, too—with good reason, I think (read the comments on that post). I don't think she could win a presidential election, and if she won I don't see much reason to think she'd be a good president. I sort of like her but I think she'd be wise to stick with the activist-cheerleader role she's currently taken on. Or else go back into Alaska politics and get some more experience before venturing into the national arena again.
And speaking of Mrs. Palin: "refudiate" is the Oxford American Dictionary's word of the year. I think it's a great word myself.