The iPhone claim appears to be a reasonable one given current thinking that Apple will return to a roughly one-year interval between iPhone updates, with a September launch coming just under a year after the early October introduction of the iPhone 4S last year.
I'm always surprised when the "return to ... one-year interval" is mentioned without mentioning an obvious possible cause for the "delay" in the iPhone 4S - the introduction of the Verizon iPhone 4 in February 2011. Another way to look at it is the Verizon iPhone 4S update occurred about 8 months after the introduction of the Verizon iPhone 4.
The development of the Verizon iPhone clearly required significant effort due to the differences from the other model - CMDA, not a world phone, mobile hotspot, no simultaneous data & voice, required changes to infrastructure like iTunes to support the 2nd configuration, and testing and certification of the unique configuration. Once that was behind Apple, release of the 2 configurations simultaneously like occurred for the iPhone 4S became easier.