I also share your puzzlement with regards to her resigning.....
.....but to say she was trying for a "political comeback" is to accept that she was somehow knocked out of it in November.
The ticket lost because of the RINO McCain, the stupid anti-Bush vote, and Obama is black. Palin was the only positive on the Republican side.
MSNBC and the other TV news channels are constantly in anti-Palin frenzy mode because they fear her. She was never out of it because she was being targeted simply for the threat she poses.
That said, she may have misinterpreted the anti-Palin mode of the news outlets as negative public sentiment towards her and made a poor judgment as a result. I'll giver her the benefit of the doubt for now.
I agree that Palin was the only thing that made the McCain/Palin ticket work and that is why this decision of Palin’s I can’t help but feel was a huge mistake on her part.