After owners of the Nexus S i9023 and i9020T got an official 4.1.1 Jelly Bean OTA last night, the update has become available for the Nexus S' i9020A variant as well.
Just like before, the update can be downloaded straight from Google's servers, though Google has indicated that the OTA should be rolling out to Nexus S phones on "a number of carriers," meaning the wait for an automatic update prompt shouldn't be long.
RT @googlenexus: We've started rolling out Android 4.1, Jelly Bean, to Nexus S phones on a number of carriers with more to come. Enjoy!...
— Android (@Android) July 20, 2012
The update, which brings the Nexus S' build up to JRO03E, shouldn't wipe data during installation, but users looking to flash manually will need to be running a custom recovery (like ClockworkMod) and a stock ICS ROM (since the update will check for build IMM76M).
assert(file_getprop("/system/build.prop", "ro.build.fingerprint") == "google/sojua/crespo:4.0.4/IMM76M/367151:user/release-keys" ||
file_getprop("/system/build.prop", "ro.build.fingerprint") == "google/sojua/crespo:4.1.1/JRO03E/403059:user/release-keys");
To grab the OTA, just hit the appropriate link below (for your convenience we've set up a few mirrors) and flash as normal.
Downloads (MD5 – bb6563221ff84b5da9739da7383ac528)