The final release of Android M won't be here until this fall, but the good news for developers and other adventurous users is that Google is distributing early developer preview builds for a handful of Nexus devices. The company tells us that it will provide Android M Developer Preview images for the Nexus 5 and Nexus 6 smartphones, the Nexus 9 tablet, and the Nexus Player set-top box.
As with last year's L preview, that support list may expand for the final consumer release. The 2012 and 2013 Nexus 7, Nexus 4, and Nexus 10 have all been upgraded to Android 5.1 and could theoretically make the move to Android M. That said, the original Nexus 7, the Nexus 4, and the Nexus 10 are all getting a little long in the tooth, and it wouldn't be surprising for Google to drop support for any or all of them.
Google says it has learned a couple of lessons from the L preview last year. First, it will "provide a clear timeline" for the update, something the company has been pretty bad about even with the Nexus, Android One, and Android Wear devices it updates directly—updates go out at different dates to different devices, which can be especially annoying if you bought Nexus hardware specifically for testing new Android versions. The company will also provide more updates to the preview build, something it didn't do much of last year.