It will probably be some weeks still before NVIDIA even publicly releases a Linux driver in the 190.xx series, but currently for those that are under NDA with NVIDIA, they have early access as a registered developer. However, a beta NVIDIA Linux x86/x86_64 driver in the 190.xx series has leaked onto the Internet via a Russian web-site.
Among the official changes in this leaked NVIDIA driver include Compiz bug-fixes, improved H.264 and VC-1 video decoding with G98 and MCP97 cores, improved broken bytes processing in H.264 on cores G84, G86, G92, G94, G96, and GT200, fixing an X Server collapse on console switching, and improved VDPAU compatibility detection. Beyond that there are also some likely changes not mentioned in these brief release notes. This NVIDIA Linux driver is at version 190.09.
As this driver is not officially sanctioned by NVIDIA for general usage, use at your own risk -- and let us know in the forums what great things you run into!