By Aidan Malley

Published: 11:30 PM EST

Hidden strings in Apple's latest iPhone firmware reveals that a major revision of the hardware is in the works and is even being tested online.

A poke around the latest iPhone firmware by Mac Rumors has found a product string for iPhone 2,1, a version of the handset that has never been publicly available or else visible in previous firmware.

The 2007 launch iPhone identifies itself as iPhone 1,1, while the current iPhone 3G lists as iPhone 1,2, indicating that it's a minor revision of a similar design. As with similar practices for Macs, Apple's choice of 2,1 implies a major update for the handset; the second-generation iPod touch is listed as iPod 2,1 and includes slightly faster internal hardware as well as a significant external redesign.

And while such company-produced leaks rarely hint at the state of the future hardware, a developer tracking ad views from PinchMedia claims to have seen requests coming from iPhone 2,1 devices; the discovery suggests that test iPhones are functioning at a level which lets them connect to the web.

Apple has until now provided few clues as to its 2009 plans for the iPhone and has left most of the talking to its individual component makers, which could potentially offer more advanced graphics, newer ARM processors or new communications chips that would permit faster 3G cellular data.