According to All Things D, Apple is set to announce a media event for September 10th, where it is expected to announce at the very least, the iPhone 5S. A budget iPhone is also rumoured to be released along with iOS 7, although it's expected that OS X Mavericks will not be released on the 10th but shortly thereafter.
While this release comes around the same time of year as last year's iPhone 5 announcement, it comes at a much more important time for Apple. The iPhone 5 did not touch their competitors in terms of screen size or performance and much of the latest iOS was plagued with glitches. This time around, Apple needs to announce a device that is leaps and bounds ahead of the competition. If Apple stays true to form, don't expect that to happen.
Forget about a game-changing phone; if Apple wants to compete with today's top-end smartphones, heck even a Blackberry Z10, they need to release a phone with something larger than a 4" screen and with more than 1GB of RAM. In typical Apple design fashion, the "S" model has never seen a bump in screen size or RAM and if Apple stays true to their past, they need to skip the iPhone 5S and go straight to the iPhone 6.