The rumor comes from IGN, who claim to have inside information from the retailers.
The three retail chains, all of whom independently pointed to Friday, November 25, as the hardware launch day, received email describing launch data late Monday. Launch day games have been re-assigned from early November to Monday, November 22, as potential first day ship dates. When contacted, Microsoft would not confirm or deny the information. In previous official announcements, Microsoft has said Xbox 360 will vaguely launch this fall.
It seems Microsoft was hoping to get the console out sooner but wanted to give developers a bit more time to finish up a few more titles for the launch. This means that Microsoft will be launching the Xbox 360 on the day after Thanksgiving, or already one of the busiest shopping days of the year.
(ign’s post about the release)