This phone is sold in Portugal and other European countries.
EDIT: I inspected the clean install rom and it seems it will work only for the I9020 model. Further analysis is needed.
If you have the old 2.3.6 version you can upgrade to 4.0.3
It is not possible to manually upgrade from 4.0.3 to 4.0.4 using the safe recovery because ICS roms need the OTA notification, so you must follow this tutorial to ROOT it via ClockworkMod Recovery image.
The images for the upgrades or clean install can be obtained here.
This is a sensitive operation. Do it at your own risk.
Finally, Google sent the OTA update. My Nexus S now runs a stock 4.0.4 version.
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