It ‘was announced officially released the source code of Android Jelly Bean 4.1.1 in AOSP (Android Open Source Project) and the binaries of Android 4.1.1, which are already available to download for the Galaxy Nexus (GSM and CDMA) and for the Nexus 7. The fact that there is a “1” over (4.1.1) means that Google has already taken steps to upgrade Jelly Bean Galaxy Nexus, Nexus S and Nexus 7 and that the new version of Android has been improved regarding lag and bug fixes .
If you are interested developer, you can download the binaries for Nexus 7 and Galaxy Nexus through the link at the bottom, while Motorola Xoom and Nexus S codes are not yet available:
Galaxy Nexus (GSM – CDMA)
Nexus 7
Sposor Link: