According to BestBuy.com, Halo 3 is set to release on November 16, 2006. Conveniently, that date is one day before Sony's PS3 is set to release. Microsoft and Bill has made it clear that Halo 3 and the PS3 will be released on the same day. This date is just barely off so I'm not going to call the police.
This date, via BestBuy, sounds accurate although it has not been confirmed. If the date is accurate then gamers will be on a rampage getting to their nearest gaming store. Also, this date is about a week before Black Friday, the biggest shopping day in the US, and just before Christmas.