As expected, Apple is confirmed to be holding a media event on 12th September. The event will be held at at the Yerba Buena Center for the Arts in San Francisco, the same venue where Apple unveiled the new iPad.
The invitation reveals nothing much other than the date and and a large "5" that appears in shadow beneath the "12". It is likely that the "5" refers to the next generation iPhone, which is commonly called the iPhone 5.
The date has previously been reported by iMore, and Jim Dalrymple of The Loop who has a proven track record of confirming launch dates for Apple's products. It is rumored that Apple will be holding a separate event in October to launch the alleged iPad Mini.