According to BGR:
One of our high-level AT&T sources just informed us that an AT&T Vice President has confirmed to several employees that the iPhone 5 is slated to launch in early October. Additionally, the VP communicated the following to a group of managers: “Expect things to get really, really busy in the next 35-50 days, so prepare your teams accordingly.” Apple is widely expected to announce the iPhone 5 in a late September event with a release set for early October.
This seems to collaborate with earlier rumors that pointed at an October the 7th launch of the device, with pre-orders starting on the 30th of September. Naturally this is all speculation and those dates could easily change, especially if Apple is looking to shake off the rumors, but given that October 7th is less than two months away, it does not seem too long of a wait.