Bernstein interprets her favorables:
Not only is the 80% favorable number [among Republicans] (with a 4:1 favorable ratio) nothing special, but she just doesn't do very well in ballot test questions. She's at 16%, tied with Huck for second behind Romney, in the latest Gallup. Given her significant advantage in name recognition, it's pretty clear that a lot of Republicans who say they like her also have very little interest in voting for her for president.
As I've said before, I'm not going to predict a winner at this point for the Republican presidential nomination in 2012. What I will try to do is to interpret the evidence that we see. And to the extent that the early polling is important, what it tells us is that Sarah Palin is a legitimate contender, but hardly a juggernaut, and hardly impervious (yes, even among Republicans) to negative stories in either the nonpartisan or the partisan press.