Given the following context:  Martin O'Donnell confirmed Halo 3's soundtrack would see a commercial release in a Bungie podcast. O'Donnell also stressed that the soundtrack would not be released at or near the release date of the game on September 25, 2007. The soundtrack was officially announced on October 17, 2007. The score to the game was used extensively for marketing purposes, even before the release of the game. The first piece heard was entitled "Finish the Fight", and was used in the announcement trailer for Halo 3 at Electronic Entertainment Expo 2006. This piece was accented with O'Donnell's well-known Halo theme, which now included a trumpet fanfare and heavy brass section; O'Donnell stated "I want the viewer to have a feeling of anticipation and wonder for the first fifty seconds or so, up until Master Chief is revealed and they realize that it's Cortana trying to tell them something." The track opens with a piano section written by Matt Daspit, uncharacteristic for the series at that point; O'Donnell suspected "no [other announcement at E3] would start with a piano", thus grabbing attention. O'Donnell designed the opening to lull the listener into a sense of suspense, then wonder; "I want them to feel pride and longing the moment Master Chief walks out of the smoke." he said. "I want them to be left with that, 'I can hardly wait to play this game' feeling". Another reworked theme from Halo was used as the background music for the Halo 3 E3 2007 trailer; O'Donnell later offered this track for free online.In addition to the music composed by O'Donnell and Salvatori, the announcement of the Halo 3 Soundtrack was followed with a call for entries to all artists or bands to submit their own original song to be included on the final CD. The submissions were judged by O'Donnell, producer Nile Rodgers, and other artists including Steve Vai. Rodgers stated that more than 21,000 songs were entered, and at least 30% were "amazing"; the winner was Greg Haupt and his band Princeton, whose song "LvUrFR3NZ" appears as the final track on the...  answer the following question:  What was the date Halo 3's soundtrack was released?
October 17, 2007