The iPhone/iPod touch OS 2.1 software which revealed some upcoming features may also have uncovered the existence of a new iPod touch.
According to iPhoneAtlas the firmware contains a reference to an iPod labelled "iPod2,1" the current iPod touch is known as "iPod1,1".
In contrast the first generation iPhone is labelled as "iPhone1,1" and the iPhone 3G "iPhone1,2", these denominations do not change for storage differences.
In the past couple of years Apple has refreshed the iPod product line in September, it is likely that Apple plains to do this again this year.