Last week, Adrian Ludwig (Lead Engineer for Android Security) and Venkat Rapaka (Director of Nexus Product Management) posted a blog entry on the Official Android blog, announcing a change to the Nexus update policy:

“Nexus devices have always been among the first Android devices to receive platform and security updates. From this week on, Nexus devices will receive regular OTA updates each month focused on security, in addition to the usual platform updates. The first security update of this kind began rolling out today, Wednesday August 5th, to Nexus 4, Nexus 5, Nexus 6, Nexus 7, Nexus 9, Nexus 10, and Nexus Player. This security update contains fixes for issues in bulletins provided to partners through July 2015, including fixes for the libStageFright issues. At the same time, the fixes will be released to the public via the Android Open Source Project. Nexus devices will continue to receive major updates for at least two years and security patches for the longer of three years from initial availability or 18 months from last sale of the device via the Google Store.”

Nexus aside, I hope other carriers also have clear policies about updates.

Read the full announcement here:
http://officialandroid.blogspot.com/2015/08/an-update-to-nexus-devices.html?m=1