Ars Technica reports that a property list file in the iPhone OS 3.0 beta reveals the existence of four unknown products. The file references products known as "iPhone3,1", "iPod3,1", "iFPGA", and "iProd0,1".
These products are listed in addition to entries for the existing two iPhone models (known as "iPhone1,1" and "iPhone1,2") and two iPod touch models (known as "iPod1,1" and "iPod2,1"). An entry for another unknown model, "iPhone2,1" was discovered in January in the iPhone OS 2 software and revealed to have been spotted on ad delivery networks as early as October 2008. That model is also listed in the iPhone 3.0 property list file.
The file, /System/Library/AppleUSBDevice/USBDeviceConfiguration.plist, lists details about the USB configuration of the various iPhone and iPod touch models, as well as the device ID and product names. The same file in iPhone OS 2.2.1 lists the original iPhone, iPhone 3G, and first- and second-gen iPod touches, referred to as iPhone1,1; iPhone1,2; iPod1,1; and iPod2,1 respectively. It also lists an unknown iPhone model, labelled iPhone2,1, which starting turning up in web server logs as far back as October 2008.
In addition to these references, USBDeviceConfiguration.plist in iPhone OS 3.0 beta contains references to iPhone3,1; iPod3,1; iFPGA; and iProd0,1. All of the products are assigned unique productID numbers, though all are assigned a productString of iPhone. These details are reported to Mac OS X when the devices are plugged in via USB, and would show up in System Profiler, for instance.
Steven Troughton-Smith, who spotted the entries, is the same developer who activated tethering on the iPhone OS 3.0 beta yesterday. He speculates that "iFPGA" may be a device that utilizes a field-programmable gate array. The numbering designation of "0,1" for the "iProd" device may signify that it is a prototype device of an unknown type.
No other details on the products have been discovered, and there is no word on when or if they may be ready for release.
Update: Boy Genius Report is also reporting the existence of an "iPod2,2" entry, which we've confirmed.