In June 2010 Sarah Palin reached the nadir of her popular support as measured by the aggregate of polling firms as collected by Pollster.com As this is an aggregate it is unimpeachable and reflects no bias, except possibly that of polling firms, but even that is smoothed out across so many polls.
The chart since then is showing a slow but steady rise, which is the best rise, as it reflects a positive, considered reflection on behalf of the public rather than a kneejerk reaction, one way or the other, to some event.
Of particular significance is the fact that in the two latest polls Palin's unfavorable rating has fallen below 50% which in the case of the latest AP-GfK poll represent a five point drop allied to a five point rise since their last poll, taken less than a month previously. At this current pace it would seem inevitable that by election day 2012 Palin's ratings in this poll would see her favorables well into positive territory. Certainly the current 8 point polling gap between Palin and President Obama is, on these trends, a minor matter, and is approaching the margin of error.
Nb.I have filtered out the CBS poll which one glance at will show why-it bears no relation to any other poll in the chart as regards methodology. But even with it included the trend is still very much the same.