Nexus devices will now receive monthly security updates from Google, in addition to their usual platform updates. Starting now with the release of the Stagefright exploit fix, Google will be pushing out security updates, and notifying its partners on a monthly basis. Samsung has also already committed to fast tracking security updates with monthly fixes.
With Google's existing security measures, less than 0.15 percent of devices that installed apps from Google Play installed any type of harmful app. Security is extremely important, and the monthly updates is yet another way that Google will help keep its users safe.
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.
Google is also still committed to supporting Nexus devices with platform updates for two years, and security patches for three years, or 18 months from the last date of sale in the Google Store.
Source: Official Android Blog