According to the AllThingsD technology blog, The iPhone 5S is looking as if it will be launched by Apple officially on the 10th of September.
While the blog listed no sources for the information, it said that in a special event next month Apple will reveal it’s latest smartphone offering to consumers.

Apple has yet to confirm if this launch date is correct.
The proposed event would see the launch of two products, including the ‘5C’ a new Apple device which has been leaked online. It’s said to be a cheaper version of an iPhone with a plastic case.
It was Sonny Dickson, a teenager living in Melbourne Australia who leaked the images of the cheaper smartphone in July.

Leaked iPhone image which suggests that this is the outer plastic case of the iPhone 5C.

In terms of the new iPhone 5S, the major feature will be a fingerprint scanner, which would greatly enhance the smartphones security capabilities.
In 2012 it was reported that Apple acquired the fingerprint security company AuthenTec for an estimated $US356 million.

This is a photo of the iPhone 5C cases.