Halo 3 rumor will be released in North America on November 15. The website claims to have been given this information by an anonymous exec in Microsoft's Xbox group.
The website also reports that Halo 3 will be released in three editions: Legendary Edition will cost $99.99 and will include "three bonus discs of extra content and a collectible replica of a Spartan Mjolnir Mark VI helmet", Limited Edition will cost $69.99 and will include "special bonus content especially for the Halo enthusiast" and Regular Version at the usual $59.99.
With the info coming from an anonymous source, the launch date is still very much a rumour. Whilst a winter release would seem likely, late last year there were some murmurings that the game would be released much sooner than people were expecting - perhaps in the summer.