All great developers are waiting for this news from the day when Android 4.0 Ice Cream Sandwich was announced, and now google decides to release the source code of Ice Cream Sandwich, it is three days before Galaxy Nexus launch. The Ice Cream Sandwich SDK is released for few weeks, developers have succeeded in building Android 4.0 ICS roms for several phones, bug after ICS source is out, developers can now handling more important things by analyzing the source code, and that will be the Real AOSP Android ICS firmware.
The ICS source tree contains all of Android system codes and modification history, include the Android 3.2 Honeycomb, however, google wants all developers focus on Ice Cream Sandwich, “there are no tags that correspond to the Honeycomb release.” google said.
This is actually the source code for version 4.0.1 of Android, which is the specific version that will ship on the Galaxy Nexus, the first Android 4.0 device. In the source tree, you will find a device build target named “full_maguro” that you can use to build a system image for Galaxy Nexus. Build configurations for other devices will come later.
Check for the original post on Google Group forum : ICS is coming to AOSP