We’ll finally know what those new iPhones are called on September 12, according to CNET - likely September 13 in Australia. The invitation CNET received doesn’t specify what products will be announced or when said products would ship.
Instead, it asks invitees to “gather round” — a joke about the impressively circular Steve Jobs Theatre that the event will be held at. The theatre is on the Apple campus in Cupertino, which is closed to the public, so if you want more details you’ll clearly need to follow Gizmodo’s coverage on September 12-13.
As for what will be announced, we expect at least three new phones. There are also rumours of new Apple Watches and a new iPad Pro with Face ID. Whether those rumours will bear out will be determined two weeks from now.