Reports are circulating that Apple is staffing up for the fall as the back-to-school season gets into full swing. An added element to all this is that Apple will be launch the new iPhone 4GS or 5 around the time students follow campus stores and, likely, Apple stores for their mobile gears to tackle the new school year.
We can safely assume that the new staffing will be for both purposes. Therefore, it does not give us additional information to pin down a timeframe for the iPhone launch. My guess is that I'll be lining up right around early September. How do I know that? I don't. It is just a gut feeling.
Having said that, there is one way we can know for sure. Apple will have to hold a media event for the iPhone unveiling. The time of this is critical. If we are going to see the iPhone in early September, that would mean Apple will be holding its event about two weeks before it goes on sale. An early September launch could mean that we'll be learning from Apple in about three weeks.
Another way to look at it, we can keep an eye on the iOS 5 beta progress. We are about half way there with the beta releases from Apple. In the past when Apple held developer events to introduce new iOS versions, Apple held the event in April with iPhone launches about 8-10 weeks later. Going by this fact, we are looking at an iPhone launch early September as well.
I think these approaches are a better measurement of gauging when we'll see the next iPhone rather than "trusted" sources or leaks.