You don't like it, but it's true.
Sarah Palin is in their heads. She is impacting elections around the country like no other single person.
Two points there.
First, the "not a front-runner" tag applies to her chances as a presidential candidate. She's not polling as high as others in that regard, nor has she done well in the straw polls that have recently started (they are pretty worthless, I'll admit).
As to "impacting elections," I will grant that she's had an effect on party primaries. Whether that carries through to the general election remains to be seen.
What appeals to the party faithful does not necessarily appeal to those who are not registered as Republicans. It's possible that a Palin endorsement could be unhelpful in the general election.
Sarah Palin wins 2012 Right Nation poll: Chicago rising
http://www.freerepublic.com/focus/f-gop/2593517/posts