While Apple’s first four iPhones all launched in the early summer, the iPhone 4S broke away from that pattern, launching in the fall instead. And according to Japanese blog Macotakara, the next-gen iPhone (presumably the iPhone 5) will follow that same pattern, and will be launched in September or October.
According to Asian reliable source, next iPhone will be released in September or October , and this cycle seems to be kept for years.
The report also claims that Apple will be keeping that timeframe long-term for all iPhone releases in the foreseeable future. MacRumors and iMore have also both independently reported (from separate sources), that Apple is leaning towards a fall launch for their next handset.
iMore’s report, however, is a bit more specific, claiming that the next iPhone would feature LTE connectivity, and would be launching this coming October.
At any rate, we’re still a long time off from the launch, and a lot can change over the course of several months.