Yesterday evening, Google announced via Twitter and Google Plus that it has started to roll-out Android 4.0.4/Ice Cream Sandwich to the GSM/UMTS Google Nexus S, the Motorola Xoom WiFi and the GSM/HSPA+ Samsung Galaxy Nexus, which was the first device featuring Android 4.0. Furthermore, Google confirmed that it will rolling Android 4.0.4 to more devices in the coming weeks. While Google hasn't released a change-log, it said that Android 4.0.4 will feature general stability improvements, better camera performance, smoother screen rotation, improved phone number recognition and more.
As always, this will be a staged roll-out which means not all devices will receive the update and upgrades at the same time but it can take a couple of weeks that your device will receive its Ice Cream Sandwich-love from Google. It should automatically notifies you about availability; however, in the meantime you can also check manually from the settings if your device is ready to get Android 4.0.4.
Cheers ~ Arne