Earlier this week Google officially unveiled Android 6.0 Marshmallow as the next version of the Android operating system, and although plenty of what would be included in the new version of the OS has been known since Google released the first Developer Preview of Android M back at the end of May at Google IO 2015, the actual tasty treat which represents this version was still a mystery. Since the first dev preview was released earlier this Summer, Google has released two other versions of it each with some new additions to the software which are expected to make their debut in the consumer-ready release. The second dev preview was released out to users earlier this Summer as well while the third and final developer preview for Android 6.0 Marshmallow was just released this Monday when Google announced the official version name.
When the dev previews go out Google launches these in the form of a flashable image, and if you're somewhat familiar with the process and follow the steps it isn't too difficult to get things going. Google has also released over-the-air downloads for each of these previews and they've started to already do the same for this last release, although it may still take a few days or more before all supported devices have it show up. Some users have already gotten their hands on them though which has led to the OTA download links being posted that can be flashed and installed similar to the way users have been able to do since Monday with the factory images.
As of right now not all OTA links are available, and at the time of writing it seems only the OTA links for the Nexus 5, the Nexus 6, and the Nexus 9 have been posted. That leaves out the Nexus Player as of yet, however the factory image files for all four of those devices are listed on the original download page Google posted earlier this week. It should also be noted that these OTA links are for build MPA44I which Google actually pushed out yesterday, and not the for the build that was released on Monday. Users attempting to install these OTA links will also need to be doing so with an unmodified device without root. When and if the link for the Nexus Player pops up, we'll post it here.
Nexus 5 : hammerhead MPA44I
Nexus 6: shamu MPA44I
Nexus 9: volantis MPA44I