From this it appears that Governor Palin has full right to fire her Commissioner of Public Safety for no cause at all.  She also has the right to fire him for cause.  The only reason she cannot fire him is for an inappropriate cause.  In this case, the Troopergate investigation was unanimously endorsed by the interim legislative council:

to investigate the circumstances and events surrounding the termination of former Public Safety Commissioner Monegan, and potential abuses of power and/or improper actions by members of the executive branch,

The potential abuses included:

1.  Firing Walt Monegan, the Commissioner of Public Safety for a personal reason.

2.  Lying about the reason for firing him.  

In the same way, the U.S.attorney firings were investigated by the Justice Department.  One of the conclusions of this report was

In sum, we believe that the process used to remove the nine U.S. Attorneys in 2006 was fundamentally flawed. While Presidential appointees can be removed for any reason or for no reason, as long as it is not an illegal or improper reason, Department officials publicly justified the removals as the result of an evaluation that sought to replace underperforming U.S. Attorneys.

By giving a false reason for the dismissals, the Bush administration lost its right to dismiss the U.S. Attorneys without cause.  In the same way, by giving a series of false reasons for dismissal of Walt Monegan, Sarah Palin lost her right to ask him not to serve.

The parallels are important because the way Sarah Palin governs in Alaska presages how she will govern in Washington D.C.  Making decisions on the basis of personal or political considerations instead of on the basis of how to govern best has left us in the mess we are in now in the nation. Sarah Palin's actions in dealing with her Commissioner of Public Safety leads us to anticipate more of the same if she and McCain move into the executive office of our nation.