Accessory manufacturer tipped off about the date
OK, this is by no means certain. But there is a strong rumour that the new iPhone 5 will be available from 21 September.
That's according to the App4phone.fr site, which claims to have spoken to source in one of the large Chinese accessory manufacturers. That source claims Apple has passed on a few details about the new iPhone, including the shelf date.
If that's the case, Apple is likely to officially unveil the phone 10 days earlier. This is where the doubt creeps in. That date is 11 September, which obviously has wider significance, so Apple might want to avoid launching hardware then. It could easily be a day earlier or later though.
We're not basing our schedules around that date just yet, but September has been talked about before, so there's every chance it could be right. If you have an upgrade due, it might be worth using that date as a rough guide.
Source: Cult of Mac
Image mock-up: MacRumors