Cyanogenmod is an alternative Android firmware which can flashed to get software tweaks, performance optimizations and other additional customizations not possible with the stock Android provided with the phones.
It is extremely popular with geeks who like to tinker with Android based devices.
Cyanogenmod 9, was a version of this popular community firmware based on Android 4.0 Ice Cream Sandwich. This release has been officially declared as stable.
The news comes even weeks after the work for the next release, Cyanogenmod 10, has already started.
The stable release was announced first for the Samsung Galaxy Nexus, but the Cyanogenmod servers are already busy churning out the stable releases for all the other popular devices as well.
Giving an explaination as to why the core Cyanogenmod team even bothered to make a stable release, when they had already started their work to match Android 4.1 Jelly Bean's Cyanogenmod 10 firmware, the official blog answers : "we don't like to leave things incomplete".
With this relase the core team has decided to stop the nightly builds for CM9, as it is popularly known, and is focussing completely on CM10.