In The Help, how does Skeeter challenge her society?

In the Kathryn Stockett's novel The Help, Skeeter (Eugenia Phelan) challenges her society by writing and publishing a book describing experiences that several black women have had working as maids and nannies ("the help") for white families. This is a challenge because the white society, up until that moment, hasn't been confronted with black people's perspectives in such a way.
The white citizens of Jackson don't all have the same feelings towards their black neighbors; their attitudes range from openly hostile, such as Hilly's, to sympathetic, such as Skeeter's. The majority is simply indifferent. (Only Celia, who belongs to the lower class in the white society, seems to be clueless about the social divisions between whites and blacks. She treats Minnie as equal, but Minnie originally does not take it as the sign of Celia's kindness; she instead sees it as her incompetence.)
Skeeter's book forces white readers to put themselves into these black women's shoes, and thus realize that these women suffer and love just as the readers do—in short, that they are every bit just as human. This is a challenge to the ones who, before, were indifferent; they wake up and feel guilty that they have allowed wrong to be done for so long. But, especially, this is a challenge for the ones like Hilly, who have been trying to enforce and perpetuate the injustice. Skeeter's book exposes them for what they are, and they must now face the consequences.