iMore wrote that Apple is planning to debut the new iPhone at a special event on Wednesday, September 12, 2012, with the release date to follow 9 days later on Friday, September 21. This information comes from sources who have proven accurate in the past.
iMore: “The iPad mini will be announced at the same September 12 event, as will the new iPod nano. We haven’t heard a release date for the iPad mini yet, but it could be the same as the iPhone 5. It seems likely the new iPod touch will make an appearance on September 12 as well, though we haven’t heard any specific information about that yet either.”