Android M Developer Preview 3 delayed, will be a "near final" release
Following Android M Developer Preview 2, this month, Google was supposed to launch Android M Developer Preview 3 for select Nexus devices. However, we're now learning that the release is being delayed. The info was shared by a Google employee via the Android M Developer Preview community page on Google+, so it's as official as it gets.
The reason for the delay is that Google wants Android M Developer Preview 3 to be "a near final release", and needs a little bit more time to work on it. In other words, the new Developer preview will likely be available pretty soon, but, for now, Google doesn't have an exact launch date to share with us.
Google is expected to introduce not one, but two new Nexus smartphones as the world's first Android M devices: one made by LG, and another one made by Huawei. Both could be released in October. That's also when Android M should get its final name, as well as a version number (which will likely be 5.2, not 6.0).
Android M is an incremental upgrade over Android 5.1 Lollipop, bringing features like a streamlined interface, enhanced volume controls, individual app permissions, improved battery life, and more.
source: Google+ via Android Police