Palin's problems will be the same from here to eternity, in perpetuity.
(1)- She is too socially conservative, which makes the independents run away. You can't win without the independents in the center these days. Either base is too small to win on party loyalists / ideologues alone. Obama had damn well better remember this or he's done in '12.
(2)- She is widely regarded to be unintelligent and uneducated. She consistently says things that are either completely false, or very poorly thought out. This won't scare away too much of the loyal base, but it is completely the wrong persona to have to try to woo independents. The nature of an independent thinker usually means a greater intellect anyway, as you're not tied down to arbitrary talking points that political parties glom onto. So many partisans of both sides exemplify the basest stupidity by their blatant hypocrisy in the examples of their support and/or condemnation. To a free thinker, this is ghastly. Her faux-folksy gee-whiz persona only adds to this problem.
(3)- Resigned from AK governorship after a very brief service. Again, this erodes confidence and the ability to garner support from anything but the 'base'.
(4)- Similar to Hillary and Obama, she does face legitimate challenges in that she has and will continue to face discrimination from a certain section of the populace. Racism and sexism aren't fairy tales. As an American, I'd love to believe that we were really moving forward away from these problems, but some weird post-2000 hysteria is catching on that is seeing the ranks of groups like AB and other xenophobic/violent affiliations skyrocket. The idea of a woman or a minority in a leadership position is anathema to many, and it crosses political lines somewhat.
In short, she is full of fail. Yes, the media will continue to parade her around. Yes, she will make a lot of $ from her books. Yes, she will continue to get coverage as she inevitably says more dumb things. Have no illusions that the left is 'afraid' of her in any way though. She is the best thing that can happen for the Democrats. The democrats have generally failed to impress, and imho are losing the independent support (the D's losing this support does not mean that they immediately shift to the R's however). There are lessons here for all. Democrats need to be cognizant of the need for both some party solidarity as well as the need to pass legislation that is well received by both their base AND the independents. They need to not be overconfident. The Republicans, I don't know. Right now they're going 150mph in the wrong direction. Getting hysterical and letting the fringe whackjobs take center stage is incredibly dangerous, as it will scare the holy shit out of the Independents they desperately need. The Republicans desperately need to purge the nuts and get a clear and honest message out, or they're cooked again for '10 and '12.