Google has just made the fourth Android N Developer Preview available for download. This update includes a final set of APIs so developers can begin compiling their apps and publish them in Google Play. Developers will also be able to run alpha and beta tests of these apps that target API 24 through Google Play if they wish.

Android N beta

From the official announcement:

Now that you have a final set of APIs, you can publish updates compiling with, and optionally targeting, API 24 to Google Play. You can now publish app updates that use API 24 to your alpha, beta, or even production channels in the Google Play Developer Console. In this way, you can test your app's backward-compatibility and push updates to users whose devices are running Developer Preview 4.

You can download the images to flash right now, or wait a little bit longer for the OTA's to become available.

Android Nougat