A new report says that iOS beta 6 will be released next week as planned, but that will be the last beta. BGR is saying that Apple is planning to release the iOS 7 GM to partners on September 5th, five days before the expected announcement of the iPhone 5S. Partners and Apple employees will get the iOS 7 GM and have just five days to test it before the announcement.
Assuming everything looks good and there are no major problems, Apple will then release iOS 7 GM to developers on September 10th after the event. Still no word on when the new iPhone and iOS 7 will be released to users though.