Sources for TUAW have discovered references to an "iPad 3,1" and "iPad3,2" in the USB device files of the developer build of iOS 5 issued Monday.
That contrasts with code from the iOS 4.3 beta, which referred to the three different versions of the second-generation iPad: "iPad2,1," "iPad2,2" and "iPad2,3." Each of those models went on to become a shipping model of the iPad 2, namely the Wi-Fi, GSM and CDMA versions.
It should be noted, however, that not all "model registrations" reference products that will see the light of day. For example, the device file "iPhone3,2" never became an actual product, although the "iPhone3,3" went on to become the iPhone 4 for Verizon.
Apple has reportedly already begun certifying components for the iPad 3. It has been suggested that Apple's next-generation tablet will feature a Retina-like display with a pixel density close to that of the iPhone 4.
The iOS 5 beta still contains references to Apple's next generation of iPhones: "iPhone4,1" and "iPhone4,2." Those references first appeared in a pre-release version of iOS 4.3 earlier this year.
People familiar with the matter were also surprised to find no references to a fifth-generation iPod touch in the iOS 5 beta USB device files. While the lack of a model registration in no way rules out the likelihood that Apple is working on an update to the device, sources suggested that the omission indicates Apple will highlight the next-generation iPhone at an event this September, rather than the typical iPod refresh.
For more information on new features of iOS 5, see AppleInsider's ongoing series, Inside iOS 5: