Is the HTC already for sale for devs?
Just did a bit of research. HTC Vive units aren't out yet, and Vive integration has only just been announced by Epic but hasn't been included in Unreal 4 as of yet. I'm assuming they would make the coding generic, similar to how the code for the various types of gamepads is all the same and is handled internally, you just need to assign actions to each generic input.
I swear I saw a story about a Vive game already having been released, though. Some stupid simulator game.