Google has finally released the Android 6.0 Marshmallow factory images for their four devices including Nexus 5, 6, 7 (2013) and 9. Last week they launched Nexus 6P and Nexus 5X that already comes out of the box with this newest operating system. Telus hinted about these updates a week ago.
If you are using any of these Nexus devices, or if you are a developer, you can download the Marshmallow images right now from Google Developers site for the respective devices. They have also provided the step by step process of flashing the ROMs but if you are not willing to do it manually, you will need to wait some more days or weeks. Google may roll out OTA updates very soon.
This new OS brings in several new features including App Permissions, Now on Tap, USB Type-C, Mobile Payments, Fingerprint Support, and many more enhancements. You can check the complete list of features here.