I kept reading your comment expecting it to retort at some point; but no, you're interested in the controller.
From the pictures, as it mentions nothing in text, it looks like they have setup dual zones on the trackpads. If they do allow user defined settings, I hope they will allow you to adjust different precisions on the areas - allowing for use of the outer ring as quicker turning, faster running and the inner rings for more precise aiming and walking. That would definitely help a transition for PC gamers, whose mice can be swapped across a mousepad quickly or slowly for fine tuning to the gamer. Many gamers also use a button on their mice to realtime change the DPI for more precise aiming.
The Valve page mostly talked about mechanical and electrical design openness, but if the input mapping api is open too, I'm sure they'll be as many mapping options as there are game mods.
From the pictures, as it mentions nothing in text, it looks like they have setup dual zones on the trackpads. If they do allow user defined settings, I hope they will allow you to adjust different precisions on the areas - allowing for use of the outer ring as quicker turning, faster running and the inner rings for more precise aiming and walking. That would definitely help a transition for PC gamers, whose mice can be swapped across a mousepad quickly or slowly for fine tuning to the gamer. Many gamers also use a button on their mice to realtime change the DPI for more precise aiming.