From the graphics programmer perspective? Nothing radically different at all. It's the same real-time rendering techniques that have existed for a while. VR is

From the graphics programmer perspective? Nothing radically different at all. It's the same real-time rendering techniques that have existed for a while. VR is only different in design methodology really (and performance requirements, as noted in another comment). But in terms of programming, there's no huge leap between graphics programming for a flatscreen or VR game.