Yes guys, I searchedfor this on the forums with no results I think that in-game there should be a fully navigatable interface for xbox controllers because right now you can only use it with a mouse, so if you had a Gaming HTPC you could just use an Xbox/PS controller to play since other games 100% support controller functionality. When you go from Steam Big Picture (which can use controllers) to the game you need a keyboard and mouse to actually get in, and I think the main menu needs to be able to be controlled by a controller for user friendliness. I know it won't be a big priority for it but it's just an idea right now.
At the moment, to enable controller navigation you must click on the game at least one time. The controller navigation won't work until you click on the game. When you click, you can then use the DPAD to navigate.