Factory images for the Pixel and Pixel 2 family, the Pixel C, the Nexus 6P, and Nexus 5X are available at the Google Developer site and can be manually installed today, and OTA updates are expected to begin shortly.
Along with the security update and patches that apply to every Android device, some bug fixes and software improvements are inbound for Google's family of devices. These range from the boring (but still important) things like improved RSA key parsing to more visual and user-facing fixes like better settings icons and improved call quality over Bluetooth. A handy chart is in order.
As always, it's recommended that everyone with a supported Nexus or Pixel product accept the update when it arrives. Improved device security and functionality is well worth it. If you would rather not wait for the over the air update you can flash the factory image right now.
We've covered flashing a factory image in depth and it's where to start if this is your first time.