NVIDIA has upgraded their SHIELD Tablet software to version 2.1. This release increments Android Lollipop to 5.0.1, updates a bit of bundled software, improves localization support, and adds OpenGL 4.5. The updated landed on December 23rd, alongside their Grid Tuesday release.
The new graphics API is interesting, but its usefulness is a bit questionable. Google does not really support OpenGL on the platform, although they do not prevent companies (like NVIDIA) from providing their own SDKs. This could be a bit increase in performance for apps that are optimized for the SHIELD Tablet and possibly the Nexus 9, especially since its main features increase performance and security. On the other hand, this should increase the potential for NVIDIA's first-party releases and ports.
If you have the NVIDIA SHIELD Tablet, then this is might be week-old news. If not, the update was released on December 23rd.