Those who say that "Volume 2" has to be Halo 3 music are wrong. As posted on the front page of Nile Rogers (www.nilerogers.com, he helped Marty O'Donnell with the soundtrack), Volume 2 contains more of the music from Halo 2 and just hasn't been released yet (the official name of the soundtrack is "Halo 2 Original Soundtrack Volume 2"). Why they didn't release them both at the same time is beyond me, but Volume 2 is definitely music from Halo 2 and not some as-of-yet-unannounced Halo 3 title.
Slashdot Mirror
Those who say that "Volume 2" has to be Halo 3 music are wrong. As posted on the front page of Nile Rogers (www.nilerogers.com, he helped Marty O'Donnell with the soundtrack), Volume 2 contains more of the music from Halo 2 and just hasn't been released yet (the official name of the soundtrack is "Halo 2 Original Soundtrack Volume 2"). Why they didn't release them both at the same time is beyond me, but Volume 2 is definitely music from Halo 2 and not some as-of-yet-unannounced Halo 3 title.