updated 09:10 pm EDT, Sun June 10, 2012
iPhone 3GS supported despite older hardware
Less than a day before Apple's 2012 Worldwide Developers Conference, new iOS 6 Beta release download links materialized. Links for the new build were provided for a handful of devices, including the iPhone 3GS -- but not the original iPad, nor any iPod Touch models prior to the current (fourth) generation. All of the previously-available download links are now expired, and no longer function.
The iPhone 3GS has an older and slower processor than the third-generation iPod Touch. The main difference between the two products is availability -- the iPhone 3GS is still produced and available for free with a two-year contract from a wireless provider.
The original iPad has a faster still processor than the third-generation iPod touch, with the same amount of application RAM. There doesn't appear to be any hardware-specific reason for the lack of original iPad or iPod touch 3rd generation to be supported, given the specifications of the unit in comparison to the supported iPhone 3GS. It is possible that support for the otherwise-compatible devices may be restored in a later beta, but as neither the original iPad nor the third-gen iPod Touch are still available, the likelihood of this is considered low.
A previous version of the iOS 6 beta reportedly slipped some details of the next generation iPhone's hardware. Monday's WWDC is expected to see the release of new Apple hardware, and perhaps sweeping changes across nearly the entire product line.