Google started the rollout of the Android 4.2 Jelly Bean update for the “takju” Play Store variant of the Galaxy Nexus yesterday, as well as the Nexus 7 in the US, and now the update is rolling out to the unlocked international “yakju” Galaxy Nexus and Australian Nexus 7.
The update for the Galaxy Nexus weighs in at 74.3MB, while the Nexus 7 update is 80.6MB. Both devices get all the new features of Android 4.2, including Gesture Typing in the keyboard, Photo Sphere panorama mode in the camera, improved Google Now, and stability and performance improvements, while the Nexus 7 also gets the tablet-only multi-user feature that allows multiple users to have their own account on the tablet.
It is being reported that the update is rolling out quite slowly, so it might not be available on your Galaxy Nexus/Nexus 7 yet. Also, those who bought their Galaxy Nexus via a carrier might have to wait for a few weeks, as carriers work on approving the update.
Be sure to check for the update manually from the System updates menu in the About section of the settings on your device.