We don't really know what motivated the Palin resignation, as I noted earlier today. I do have a guess. My guess is that she has been offered her own talk show, probably on Fox TV, and has accepted.
This would give Palin a platform from which to expound, be exposed, and develop a larger following, while getting paid handsomely for do so. Mike Huckabee is going this route and I suspect it is working out well for him.
In order to tape her show Palin would have to spend a significant amount of time in the lower 48, possibly in Washington. From this vantage point trips to Iowa and New Hampshire would be much shorter.
Alternatively, Palin could do a national call-in radio show from Anchorage. This, I think, is a less attractive option as guests would be difficult to schedule.
