The significance of Palin's popularity has nothing to do with her viability a a Presidential candidate. She is an en extremely popular symbol of Middle America's disgust with the elitist political class that has recently gained dominance in our government.
What qualifies anyone to be President? An Ivy law degree and a life free of any honest work?
If truly relevant experience and accomplishment criteria were applied we would certainly not have elected Obama. He has accomplished virtually nothing in his life except to win a couple of elections against weak opponents, and then only with a totally complicit press.
Palin is and will be a force in American politics, but probably not as a Presidential candidate. Whatever her abilities and qualifications the left-leaning press is totally committed to smearing and demeaning her which will probably prevent a Presidency, but it will help other conservative/populist/non-elitist candidates. The hard-core left---especially those so numerous in the press---still don't get it. The majority of Americans reject the Obama agenda and the arrogant, elitist, and unfair bashing of Palin, Bush, and others just serves to energize Middle America.
The three recent election victories of conservative are such a clear signal that people like Bayh understand. Anyone whose head is not buried understands, but apparently Obama refuses to accept it.