"What's that song in the trailer?" seems to be the question of the moment. The answer (which has been previously posted) is Fever Ray. Below is an excerpt of an article discussing the musician and Catherine Hardwicke's aesthetic and musical inspirations.
"So far the Fever Ray contribution has been slated as only a song, but there have been rumblings, from Hardwicke herself, that Andersson will make a cameo in the film as her Fever Ray persona. She will appear amongst the wreckage of the wolf effigy, with all the villagers dancing and chanting alongside her as she herself, clad in a harvest-style costume, performs her song. Hardwicke seems to be much inspired by Andersson’s style and music, using it to capture the suspenseful distortion of the tale as well as potentially inspire the highly stylized and striking costuming. The scene with Seyfried amidst the flaming wood pieces has her masked in a simplistic yet creepy and startling wolf mask. It seems part Venetian mask inspired but also a nod to Andersson’s quirky and dynamic style on stage."
Check out the entire article here.