Apple has sent email invites for a September 12th press event to be held at 10 am Pacific Daylight Time at the Yerba Buena Center for the Arts in San Francisco. The invitations made a not-too-subtle reference to the expected iPhone 5 announcement, with an image of the number 12 and a drop shadow that forms the number 5.
We expect the event to herald the arrival, or at least the announcement, of the iPhone 5, but there could be other new products or product announcements, including a smaller iPad, new iPods, and a new iMac.
From that group, I think the mostly likely products to be unveiled on the 12th (besides the iPhone 5) are new iPods; perhaps a new Touch, Nano, and Shuffle. Late summer/early fall is the traditional time for iPod updates, and they wouldn't steal the limelight from the iPhone 5.
Here are the latest rumors about iPhone 5 features: