The next iPhone is getting closer, perhaps closer than originally expected as we hear that there will be an event planned for September 12 with a launch of September 21 for the device. Although some are referring to it as the iPhone 5, it will likely be called just iPhone or the new iPhone to move away from numbers. It will actually be the 6th generation phone.
The same source of information to iMore also indicates that the new iPad mini will also be announced at the same time as well as a new generation iPod touch.
The launch last year was held in October which put 16 months between the 4 and the 4S. This time around, if the September date is correct, it would be 11 months which means there will be about 6 months between the launch of the iPad and launch of an iPhone which is probably done for a reason.
As well as potentially launching a new generation iPhone along with a new form factor iPad, Apple will also likely release iOS 6. We also expect that iOS 6 on the 6th gen iPhone will get more features than iOS on the 4S... a bit like how Siri was added to only the 4S when iOS 5 was launched. That "extra feature" could be NFC as Passbook was listed as the new feature in iOS 6 although that is just a guess right now.
Expect to hear more from Apple sometime in August if an announcement is being made in September.