Microsoft's email to those lucky enough to get on the early access program for New Xbox Experience were told by email today that the update will be available "on or before" November 1.
Also included in the mail is a warning that any Xbox that attempts to connect to the program and hasn't been specifically registered for the preview will be blocked from accessing Xbox Live until NXE launches on November 19.
Here's the message in full:
Congratulations on your acceptance into the Xbox 360 Fall Flash Preview Program. As a member of this program you will be receiving the New Xbox Experience (NXE) System Update.
The update will be made available to you on or before November 1st. In order to receive the update, log in to Xbox LIVE with the Preview Program registered console.
In participation with this program, you should not move your storage device (hard drive, or memory unit if you do not have a hard drive) to any other console as it will also update that console. If an unregistered console is updated with the NXE update, that console will not be able to connect to Xbox LIVE until the NXE has been officially released on November 19th.
We thank you for your participation and hope that you enjoy the New Xbox Experience.
See you online,
The Xbox 360 team
Many thanks to revolting!