iPhone 4's internal version is 3,1, so what then are the iPhone 3,2 and iPhone 3,3 versions referenced in the just-posted Apple TV iOS firmware? Seth Weintraub from 9to5Mac speculates:

Verizon? Sprint? China Mobile? T-Mobile? Antennas? All very good questions. No answers yet.

To put things in context, the original iPhone 2G was iPhone 1,1, iPhone 3G was iPhone 1,2 and iPhone 3GS was 2,1. So we're looking at the difference between iPhone 2G and iPhone 3G, which mainly consisted of a new shell and new 3G radio, not the completely revved up guts the iPhone 3GS or iPhone 4 got.

CDMA (like Verizon, Sprint, or some parts of Asia), or the higher frequency AWS radios needed for US T-Mobile and new Canadian providers like Wind and Videotron are certainly possibilities. Since there are two new product versions, how about both?

And if that's not tease enough, there's also reference to a 20547 unknown device. New iPad, iWatch, iOS desktop? Who knows, but feel free to give us your best guesses in the comments.