iOS 5 likely coming first week of October
To answer a ton of questions we're getting, if I had to guess I'd say iOS 5 will likely be launched in the first week of October. Apple traditionally releases a new version of iOS to the public alongside the release of new iPhone hardware, if not a couple of days before to help balance server loads. If iPhone 5 ends up being scheduled for October 7, then iOS 5 could be scheduled for any time that week up to and including the same Friday.
That's speculation on our part, but given that last week TiPb heard Apple was moving up their internal launch date for iPhone 5 from October 14 to October 7, 9to5Mac heard likewise, and now BGR has heard the same launch window from an AT&T source, it's starting to seem more likely.
If that's the case, based on traditions, we can probably expect to see a GM candidate for IOS 5 released to developers a couple of weeks or more before that, possibly at Apple's fall special event that also introduces the new hardware.
Again, Apple hasn't announced anything and typically doesn't announce their events until a few days before hand. That also means Apple is free to change any of these timelines up until the send out invitations for the vent and announce the official launches. So new mothership headquarters-sized grains of salt all around.
But that's part of the frustration and fun of Apple.