According to people familiar with the matter, the latest beta of iOS 4.1, due to ship in the coming weeks, includes three new "Configuration Descriptors" within its USB configuration files -- all of which pertain to devices that list "Apple, Inc." as their "manufacturer" -- as can be seen in the screenshot below.
The first product, a fourth-generation iPod touch, is referenced within the code as "iPod 4,1." That particular identifier indicates the device will be the first iteration of a fourth-generation device, rather than a revision to the touch's existing design, which would have been denoted as an "iPod 3,2."
The second unreleased product referenced in the USB configuration files is "iProd 2,1." All indications are that this device represents a material update to the company's iPad, as the inaugural version of the device released this past April was similarly listed in configuration files as "iProd 1,1" prior to its announcement.
Finally, and most intriguing, is a previously undiscovered mention of a mysterious device listed only as "unknownHardware." Although the configuration files tag this device with a unique Apple product ID of 20547, it's textual descriptor is similarly listed as "Unknown- Add device descriptor info for this device."