Far be it for me to interpret actions by politicians cynically. There is a lot of analysis about why Sarah Palin resigned. I don't know anything more than most, but here is what I told a friend way back in December:
Sarah Palin should resign now and go on the speaking / pundit circuit. She is currently in the midst of her 15 minutes of fame and before it passes, she should jump on the opportunity. In particular, there are all kinds of conservative business execs who will fork out $75,000 a pop to have Palin speak at corporate functions, sales conferences, etc. This is not even to mention however much Fox is willing to pay her to be a talking head.