I've seen a couple such, right here on FR. And if you analyze things electorally, as opposed to some mythical and misleading "popular vote" poll 2 years out, you can begin to see that Sarah winning is eminently feasible.
Indeed, rather than finding such polls discouraging, I believe any polls which show Palin anywhere close to Obama are absolutely amazing, given the current free-for-all environment of character assassination against her. At some point, her detractors are going to have to move beyond personal attacks, because Sarah can and will win people over with ideas. In fact, that's what I think the Left fears most. just like they did with Reagan.
One things for sure, if Sarah runs, her critics will have to become less and less dismissive, out of sheer necessity. She will finally have to be taken seriously whether anybody likes it or not.
Once again, I'm not debating the efficacy of polls. What I would like is for people to accept that as of now there are no polls that I can find showing her beating Zero. Please, show me some.