Most notable to the Nouveau driver updates is that there's the long-awaited GeForce GTX 900 series secure boot / signed firmware support that's been necessary in order to get open-source 3D working on Maxwell, the latest generation of NVIDIA GPUs.
With this Nouveau DRM driver for Linux 4.6 paired with linux-firmware.git and the latest Mesa, open-source 3D acceleration should be working for the GTX 900 series cards. I will be running some of my own benchmarks on it this week. But before getting too excited, there isn't yet any re-clocking support and bugs are likely in the latest hardware support from this open-source, largely reverse-engineered graphics driver.
Nouveau Linux 4.6 also has the new Tegra X1 / GM20B clock driver, support for power sensors on select GPUs, and a variety of fixes.
This DRM driver pull is quite heavy with 9146 insertions and 6512 deletions. More details on the changes via this Git commit. Stay tuned for the GTX 900 Nouveau tests.