Today Google launched their new Nexus Series along with Android 4.2 Jelly Bean for the Google Galaxy Nexus and the Google Nexus 7. Unfortunately Jean-Baptiste Queru, the Android Open Source Project technical lead, announced that the newest version of Android will not be made available for the Google Nexus S and the Motorola Xoom.
Both devices will remain on Android 4.1.2, just like the Google Nexus One which was deemed too old to upgrade to Android 4.0 Ice Cream Sandwich last year.
While Google hasn't revealed the reasons behind choosing not to upgrade the Xoom or the Nexus S, it could be a result of hardware limitations. Both devices have been around for some time now so we cant complain too much. However many users have faced issues with the last 4.1.2 update which caused their devices to slow down. Its not certain if Google will choose to release a fix or decide that the user base isn't large enough to both with an update.
There is still hope for these devices through the development community, which has kept the Nexus One alive with the latest Android versions, a year after it was abandoned. Hopefully this will be the same case for the Xoom and Nexus S.
source – AOSP