I wondered in the past few days when they'd release a new beta driver. It's clear that they are working to get their drivers ready for Wayland and Mir with EGL. What will be interesting is if they implement XWayland support. From what I know the xf86-video-* DDXs all have their own XWayland patches so the closed drivers would need them aswell I guess. It would probably not be that hard for NVIDIA but, when there isn't even a version of Xwayland that is shipping with X.Org. I think they will only start working towards that once X11 1.16 ships with XWayland hopefully.
There seems to be a patch for 3.13 support.
Arch Linux has it built into the driver packages in [testing] which holds the 3.13 kernel.