As you may or may not know rumors have been going around, and are all but confirmed, that Sprint is going to get the iPhone 5 when it's released. Sprint is the only carrier to offer truly unlimited data plans, so getting the iPhone could be huge for them. People who don't want to worry about using all their data and getting charged extra each month could just go to Sprint for an all you can eat data buffet.
New rumors are saying that according to an internal memo at Sprint they are blacking out employee vacation from September 30th - October 15th for a larger phone release. This means all hands on deck for Sprint for those two weeks and it just happens to fall right into the rumored iPhone 5 release time.
This combined with other rumors of AT&T and Verizon blacking out vacation time pretty much confirms the iPhone 5 will release in the first two weeks of October. Several sites are pin pointing October 7th as the launch date which sits right in the middle of the Sprint vacation blackout and lines up with several other reports and leaks from around the web. I wouldn't hold my breath that the date is correct but the first half of October is pretty certain.
Exciting news I can't wait!