Evidence of two new iPhone devices have been found in the just released Apple TV firmware.
The iPhone 4 is referred to as iPhone3,1 by Apple. However, the Apple TV firmware contains references to iPhone3,2 and iPhone 3,3.
These references suggest iPhone 4 devices with minor hardware revisions such as possibly a CDMA version or a device with modifications to the antenna. A major hardware revision would be denoted by iPhone 4,1.
It's also possible that Apple is not planning a major hardware upgrade for next year's iPhone. This would be similar to minor changes made from the iPhone 2G to the iPhone 3G which were respectively denoted as the iPhone1,1 and the iPhone1,2.
There is also an unknown device numbered 20547 that can be seen in the screenshot below.