While Obama's message of change is real, there's a second area of change that's needed in the US and, given Palin's history in Alaska, is a change to which McCain can speak -- the cleaning up of politics. Palin, through taking on the corruption in her own party, adds to that compelling storyline.
Congress on both sides of the aisle has dirty hands in terms of pork and/or corruption. As politically partisan creatures, we tend to look the other way when the person caught with their hand in the cookie jar votes in a manner we like. We forgive them their indiscretion as having a corrupt politician that votes our way is better than a politician from the other side. The fact that Congress is given responsibility for policing themselves only exacerbates the problem.
A good house cleaning and an end to pork politics in Washington would be a tremendous legacy for McCain to leave. Obama can't provide that kind of change. He's a good man but he's a political novice and extremely partisan as his 97% partisan voting record would demonstrate. He'd have difficulty saying "no" to the pork requested by his seniors in the party. That's not saying anything derogatory about Barak Obama. He's a junior Senator just finding his way around Washington. It makes sense for him to vote along party lines while he gets his feet wet and learns the issues.
Palin does add credibility to the McCain "clean house" agenda. At least that better be his agenda as he really hasn't clearly identified what else he's running on. It's not really "the same" but it's also not something that can be clearly defined. (The GOP used to be really good at distilling an entire campaign message into 15 seconds.)
