Sources told AllThingsD that Apple plans to hold a press event on September 10th to introduce its next generation iPhone. Details on the iPhone were not provided to AllThingsD, but Apple is rumored to be working on an iPhone 5S possibly with a fingerprint sensor, beefier processor and improved camera sensor.
A spate of recent rumors suggest the company may also unveil a low-cost iPhone model to compete in the mid-range smartphone market. The introduction of a budget model would be a significant strategy shift for the Cupertino company. Traditionally, Apple has shied away from mid-range hardware and has reduced the price of its older iPhone models to appeal to the low-cost consumer.
Besides new hardware, Apple is expected to announce the availability date for iOS 7. Keep in mind this information still lies squarely in the rumor territory, but I would block that day off anyways just to be safe. AllThingsD has a pretty good track record when it comes to leaks like this.