Loren Long's illustration of Sitting Bull in Barack Obama's OF THEE I SING
Comment: The problem isn't only the one-with-nature stereotype. It's depicting Sitting Bull as a remote, otherworldly, even mythical character. The message is that Indians have vanished into the landscape just as Sitting Bull seems to be doing.
Again, if Long had drawn everyone that way, it would be okay. The ultimate problem is treating the Indian differently from whites and other minorities.
For more on semi-mythical Indians, see Bears Replace Indians in Store Window, Vanished Mound Builders in The Prairies, and Neil Gaiman on Dead Indians.