After some false hopes by Vodafone Australia yesterday, it seems the Android 4.1, Jelly Bean update for the Nexus S has begun in the earnest and this time it's for the international market.
An Android Police reader has reported receiving the 4.1.1 update on his GSM Nexus S (I9023). It's a 114.4MB update, which brings the build number to JEO03E.
If you are the impatient sorts and don't want to wait for the update to arrive over the air for your device then you can also download the update from Google's servers and flash it manually. Just make sure you are running a stock ICS ROM and have a custom recovery software such as ClockworkMod installed. And as usual, make sure you know what you are doing or wait for the OTA update.