Inspection by TUAW sources, Apple's unofficial weblog, has discovered references to two next-gen iPad models and two iPhone 5 models while going through the USB device files of the iOS 5 firmware released on Monday.

The iOS system files contains buried references of iPad3,1 and iPad3,2 and iPhone4,1 and iPhone4,2. This apparently contrasts with the code obtained from the iOS 4.3 beta which contains references for iPad2,1, iPad2,2 and iPad2,3, the three versions of the iPad 2.

However, reports by AppleInsider mentions that not all model registrations reference products 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.

Certain other reports speculate that since there are no references for the development of the next-gen iPod touch, the company is probably working on the release of its new iOS member, the iPhone 5.