My best mate works for Optus here in Australia and had a conference call with all other Optus store managers yesterday (27 hrs ago from this post). The conference call was in regards to the iPhone 5.
Firstly, it WILL be an iPhone 5, not a 4s or any of that nonsense.
Secondly, they spoke about most Optus stores (at least in the Sydney) receiving iPhone stock in the last 3-4 days in September, which makes it Tuesday 27 - Friday 30. This means an approximate iPhone release date in Australia of 3-6 October.
Each Optus store will receive an initial quantity of 10-12 of each of the iPhone 5 units. There was no information of how many iPhone 5 models there would be (in regards to possibly a cheaper model as what has been speculated)
Just a side note:
It was not spoken about as to what the specifications of the iPhone 5 would be, nor the design.
The reliability of this information is very reliable. I just thought i'd share.