Android 4.0.4 (ICS) build IMM30B is now out in the wild and ready to be downloaded. If you own a Galaxy Nexus, you can now download ICS 4.0.4 and flash it on your device. Here is the step by step guide to help you flash Android 4.0.4 on Galaxy Nexus.
Requirements: You should have Galaxy Nexus with Android 4.0.2 ICL53F (stock) to be able to install this update.
Step 1: Download Android-4.0.4-IMM30B.zip
Step 2: Rename the downloaded file to “update.zip”.
Step 3: Copy the “update.zip” to root of SD card.
Step 4: Reboot Galaxy Nexus in Clockwork Recovery.
Step 5: Select the option “install zip from sd card” and select “update.zip”.
Step 6: Android 4.0.4 update process will now begin, wait till its complete.
Now you will have Android 4.0.4 installed on your device. Enjoy.
via XDA Developers