I am not endorsing Obama however, I am not so delusional that I believe that VP Palin will ignore the dictates of the President by casting votes in the Senate that are contrary to the President’s policies not do I think VP Palin will visit Heads of State and commit America to policies without McCain’s approval.
You see, we have only ONE President.
I'm pretty certain Governor Palin did not sign on with John McCain so that she could become a doormat. Given that it's pretty clear that she's more popular than he is, I would expect they both realize that--were she so inclined--she could severely hurt John McCain politically. Of course, neither she nor McCain would want things to come to that, but that doesn't mean there aren't any circumstances where she might need to make a credible threat.
While previous VPs have not made such threats, at least not in recent times, that's largely because previous VPs have not been anywhere near as popular as their running mates. Palin's popularity caries with it an unprecedented level of political clout for a VP.