If carrier approval is October 5th, I'd expect the timeline to look like this:
September 27/28: Media invites sent
October 5: Apple presser for iOS5 ("Available Today") and iPhone 5 (Reservations accepted today, available 10/14).
October 14: iPhone 5 released.
September 27/28: Media invites sent
October 5: Apple presser for iOS5 ("Available Today") and iPhone 5 (Reservations accepted today, available 10/14).
October 14: iPhone 5 released.