I’ve been thinking about this for a while now, but after seeing Apple’s terrific financial results for the second 2011 quarter it became clear to me: a new iPhone in September makes perfect sense, in spite of all the reports claiming it would be a bad choice for the company to “delay” the release of the next-generation to the Fall skipping the usual June / July timeframe. Of course Apple hasn’t confirmed any of this speculation, but if rumors and reports from well-sourced Apple journalists like Jim Dalrymple are of any indication, it really looks like we’re going to see a new iPhone in September, not this summer. And here’s why I think it’s a good plan.

Apple sold almost 19 million iPhones in Q2 2011, accounting for 50% of their total revenue. The numbers are noteworthy for two reasons: not only did Apple manage to sell more units than the almighty holiday season (Q1, 16.2 million iPhones sold), they also expanded their overall iPhone business to other countries outside the United States – like China, where the iPhone saw an enormous rise in the quarter. Apple didn’t provide a breakdown of iPhone 4 sales Vs. iPhone 3GS sales (the older 3GS model is now sold at $49 in the US, not a bad deal considering users also get the latest iOS update with the device), but it’s clear the iPhone 4 has become the most important piece in Apple’s mobile strategy. And releasing the device on Verizon Wireless’ CDMA network helped a lot, too. If anything, it helped looking forward.

But that’s just the beginning, as everything is set to grow even bigger in the next few months. Consider this: the iPhone is available on 186 carriers in 90 countries; 88% of Fortune 500 companies are testing or deploying the iPhone (thanks to the advanced security and business features introduced with iOS 4.2); Apple is opening 40 new retail stores with a 5th massive store in China. Apple had some supply issues in Q2 following the Japan earthquake and tsunami, but COO Tim Cook said they “do not anticipate material impact in fiscal Q3” – meaning they’ve managed to close pre-payment deals for key components like LCD screens, RAM and flash storage. On top of that, 350,000 apps are already available for the iPhone, and the 400k mark should be on the horizon relatively soon. Also: iPhone sales are up 155% in the United States.

The staggering truth is, people are still buying the iPhone 4 – a device that’s now approaching its (usual) 12-month product cycle and that, if we were in 2010, should be headed for a refresh in June. But apparently, it’s not. How does that make sense? If the numbers above aren’t convincing enough, think about this: the Verizon iPhone has just begun to roll out to consumers, and we can expect a lot more sales when millions of AT&T contracts will be up in…June. Not to mention the white iPhone: assuming some people didn’t buy a black iPhone 4 because they decided to wait for the white version – well, they’ll have a reason to buy one very soon. And, again, considering that the white iPhone should also be available on Verizon in the US, it’s clear that Apple has an important card in its deck: a new iPhone model, released ahead of a month that will see millions of customers deciding whether they want to stay on AT&T, or switch over to Verizon. Either way, Apple will keep its current iPhone userbase. But what about those users who couldn’t buy an iPhone on Verizon in June, walked in the retail store and chose the most-similar Android handset? What are they going to buy this June?

And then there’s the software. Apple is rumored to be considering an official introduction of the next major version of iOS – iOS 5 – at the WWDC in June. According to several reports, the OS is a massive rewrite of the existing iOS for iPhones and iPads, featuring new cloud-based functionalities, location services, and a new notification system. By releasing a new iPhone in September, rather than June, Apple will have time to introduce the new OS to developers, let them play with it, and allow them to take their time to build new applications for it. As betas and GM seeds are released during the Summer, Apple will have the chance to officially unveil the new device and release the OS in September. Rather than shipping the iPhone 5 with an old, tweaked version of iOS 4, the iPhone 5 could ship with the brand new iOS 5 – and quite possibly some exclusive new features made possible by the improved hardware. Apple’s product cycle has become a platform cycle: Apple doesn’t sell iPhones because they’re phones, Apple sells iPhones because they’re phones that run iOS. That’s the full package: a great piece of hardware, a stable software with direct iTunes integration and access to over 350,000 apps. An iPhone 5 combined with iOS 5 and new apps built specifically for it will surely appeal consumers more than a minor iPhone 4 refresh (that’s what the iPhone 5 is said to be) running the same old OS all over again. The point being – even if the iPhone 5 is a minor hardware refresh, the software will make it shine. Otherwise, it will look good – but not great. The way I see it, that’s the plan Apple is hatching.

Last, a September release means Apple could move the iPhone against the much more profitable holiday season. If a new iPhone comes out in September, how many users are going to buy one come Thanksgiving and Christmas? Remember the golden iPod days? Right.

Still, we’re just speculating here. Apple hasn’t announced anything, they haven’t confirmed in any way a new iPhone won’t be announced in June, and as usual they will release its product “when it’s ready.” But this time, for a number of reasons listed above, I think this speculation makes a lot of sense.