Hello Droiders, Google has just pushed Jelly Bean (Android 4.1.1) OTA update for their flagship phone, Google/Samsung Nexus S. Normally this OTA update can be checked and downloaded from System Update menu on Settings. However, not all Nexus S phone get this OTA update. So if your Nexus S does not the OTA update, you can try the following trick to enable OTA update:
It may take more than once attempts to make OTA update appears, so you can repeat the step 1-4 untul the OTA update appears. This trick also can be applied on Galaxy Nexus to get Android Jelly Bean OTA update.
Have a nice try..;)