By the pricking of my thumbs, something wicked this way comes.

Sorry, but I don't think they did. The witches in the play were much more important than the mostly naked teenie goth girls in this film. While in the play they could be seen as the force that drives the action, tempting Macbeth to kill Duncan and manipulating him into killing others, I got the idea that they were only in the film to add some sex to the lack of atmosphere (as in the raunchy music video type sex scene).
This film has hardly anything to do with the play "Macbeth", a play about a man tormented by first a choice and then its consequences. Sam Worthington was certainly not the best man for the title role. He lacks both energy and variation in delivery and I was actually glad that most of the monologues were cut down in length.
It also seemed like a lot of the cast had no idea what they were saying and either the director didn't realize it or he did but was unable to make them understand.