I think Sarah has played this smart by staying as neutral as possible. Remember, she and McCain are running as opponents of earmarks and wasteful spending, and Stevens is the king of earmarks. Also, if Stevens gets off, it won't necessarily be because he is innocent, but because the prosecution screwed up.
The whole "ear mark" thing is BS especially since it's only a scandal when a Republican does it. How is an ear mark different from "district services"? It's not. The media even has conservatives believing and reciting this crap.