Since Android 4.0.3 is the "base version" for Ice Cream Sandwich, Google has added the source code for it to the Android Open Source Project (AOSP). The build supports two devices — we've already seen the update roll out for the Nexus S, but the other is a device that was also launched in direct partnership with Google: the Motorola Xoom (Wi-Fi). True to form, the enterprising hackers at XDA-Developers have already compiled it into a bootable ROM for the Motorola Xoom.
The build is certainly not for the faint of heart: the camera doesn't work and there are likely plenty of other bugs, and as an AOSP-build it also doesn't include Google Apps. All that might be the bad news, but the good news is that early indications show that Ice Cream Sandwich is showing much better performance on the Xoom than Honeycomb did. Hopefully that performance will stick as the ROM develops.
Obviously the vast majority of users shouldn't be installing this ROM until the kinks are worked out. However, given how quickly Google managed to release the Android 4.0 update for the Nexus S, our fingers are crossed that the Motorola Xoom could get a speedier-than-expected update as well — Motorola has promised it would come, but hasn't yet provided a timeline.
Meanwhile, this build of Android that has been submitted to the AOSP has a healthy chance of finding its way to more devices. As Google developer Jean-Baptiste Query put it: "This version of Android is optimized for a wide range of devices" and Google's "best release ever."
Thanks Trevor and knewman!