The report started in the Google Group called "Android Building", where Jean-Baptiste M. "JBQ" Queru a Software Engineer on the Android Open-Source Project at Google announced that the source code had been released, and that developers could download it. Of course, this is a good sign that the Galaxy Nexus will be released soon. But, it's an even better sign that the update race has begun.
As anyone in the root community knows, once the source code is officially released from Google, the Cyanogen developers of Team Douche will be working on building Cyanogen 9. The earliest updates we've heard about outside of the Nexus line has Ice Cream Sandwich hitting certain devices around January. We're pretty sure Cyanogen 9, based on Android 4.0, is likely to hit devices well before then. We'll definitely let you know when the first solid custom ROMs start hitting.
Many do point to this as the time that bigger manufacturers like Samsung, Motorola and HTC will be starting work on the upgrades for their devices, but we're not too sure how accurate that is, especially given that Notion Ink's CEO Rohan Shravan told us in September that Google had been seeding "crucial partners like chip vendors, [and] select OEMs" with ICS builds well before now. As we've said before, if a small manufacturer like Notion Ink can get early builds of ICS in order to start work on updates well before the source code release, it seems very likely the major hardware partners would also get that code.
Google has also technically released the Honeycomb source code since ICS was built on Honeycomb, not Gingerbread, but wants to focus on ICS. So, according to JBQ, Google hasn't "created any tags that correspond to the Honeycomb releases (even though the changes are present in the history.)” If you really want, the Honeycomb source is out there, but it seems a bit unnecessary with ICS being out as well.
source: Android Building Group via Androinica