The New World

The music for the film was composed by Hans Zimmer, and is very similar to the music at the beginning of "Black Hawk Down," (which he also composed) during the history of the Somali conflict, and right before it cuts into the crisis at the Aid Center/Refugee camp. My guess is the music in the trailer is something composed for the film, or trailer itself, and is probably something of Zimmer's. I wish I could find if though, because the music and voices are haunting and work very well with Malick's images.
You're right!

However, the Immediate Music track, "Ritual" appears to be uncannily similar to the one by Regan High Priestess...

Edit: It is definitely the same track. Immediate Music must have bought the rights.
It's not Rainbow Voice, right. I haven't heard a full version, can someone tell me if this is the one....I don't think it is though.
The style sounds a little like Adiemus.It was probably written for the movie.
The song is called "Summoning of the Muse" by Dead Can Dance, from the Within the Realm of a Dying Sun album. Lisa Gerrard provides the vocals.
Actually, the name of the song that we're talking about is Summoning the Muse by Dead Can Dance.
The trailer for the new movie starring Colin Farrell uses a Dead Can Dance (with the vocals of the ever lovely Lisa Gerrard) song called "Summoning of the Muse" from their record "Within the Realm of a Dying Sun."

I did a search and couldn't find it, but thought I'd post this since all my friends who saw the trailer wanted to know the name of the song, and someone else likely will in the near future.

"Trigger" - Cinetrax
"The Way Out" - Cinetrax
"Summoning the Muse" - Dead Can Dance
"Ritual" - Immediate Music
"Hallowed Ground" - Regan High Priestess
"The Arrow Drawn" - VideoHelper Music Library
"Mojo Rising" - Brand X Music

"Ritual" - Immediate Music
"Rainbow Voice" - Michael Stearns
"Drum Hits #2 Full" - Nathan Duvall
"Morbid Upsurge" - Robert Etoll
"Nuclear Escalation" - Robert Etoll
Ok, I got a copy of that song but it is not the same version as in the trailer. Is there a special name for a remix of the song that has the more upbeat tempo in the trialer?
Was wondering if anyone knows the song in TV spot. It has a femal singer that sounds very familiar.
I am looking for this song as well. And I agree that the vocalist sounds somewhat familiar.... Anyone?