Otherwise it is ALWAYS Governor Sarah Palin or Gov. Sarah Palin, or Gov. Palin.
“The only time it would be proper to use Mrs. Palin (I have even seen Ms. Palin) would be in the context of her marriage to Todd Palin; as in ‘Mr. and Mrs. Palin invited us into their home where Governor Palin discussed policy issues while Todd talked about snowmachine racing.’”
I don’t think so. In that case, the proper address would be, “Governor and Mr. Palin invited us into their home where Governor Palin discussed policy issues while Todd talked about snowmachine racing.”
That is the formally correct form.
However Sarah Palin is who she is as an individual. And "Sarah Palin" is pretty awesome, so I consider it an acceptable way of referencing to her.
But Mrs Palin (or Ms Palin) is an attempt to diminish her by giving her a title, but one which, although technically correct, is less exclusive than her actual achievement.
Right out is Joe the Hard-Coal Miner's "'Lieutenant Governor' Palin"