But I think she is not running.
Why would you think that, when she's been doing and saying everything that a presidential candidate does and says, over the last year?
If it walks like a duck, and talks like a duck, it's pretty well certain that it's a duck.
Regarding the question of, "Will she/Won't she?", she has to say that she's "still thinking about it" to keep the curtain pulled on what she's actually doing.
In truth, she really had to make her decision well over a year ago, and she did. Here's the proof: If she'd decided to stay out of the race, she would have told her supporters, so that they could focus their time, attention, and energies on another candidate of their choice.
That said, once she decided to run, she was faced with a second choice - what sort of strategy to employ in seeking the office of president. She's savvy enough to know that someone with her name recognition and massive grass roots support doesn't need to declare early in the process, as many others have to do.
In fact, it's actually detrimental to any candidate to declare early, but most are forced to, because they need to achieve widespread name recognition, build widespread support, attract donors, and spread their message. Someone like Palin already has all that, so doesn't need to open themselves up to attack and meat grinder analysis by the media or their opponents.
Reagan declared later in the process for the same reasons. Why spend monies on running a campaign or expend the energy defending oneself, when you're achieving all the benefits of a campaign on the sidelines for free?
Her campaign strategy is Big League Politics 101.