I don't blame you if your first question following the event was, "When am I getting Android 4.0 on my phone? Let's face it, there are potentially millions of users with new or semi-new handsets who really want to have that Ice Cream Sandwich experience. In other words, you love the 4.0 stuff but aren't ready to commit to a new phone all over again.
Google's founding father, Andy Rubin, participated in a Q&A session at AsiaD where he addressed the soon-to-be hot topic. According to the senior vice president of mobile, the tentative schedule has some existing devices on track to see Android 4.0 updates within "a couple of weeks after" the Galaxy Nexus arrives. So with the handset arriving in mid-November, this puts the upgrade out as early as the middle of December.
Although Rubin didn't elaborate as to which phones might be first to see the Ice Cream Sandwich update, it's widely expected that it will come to the Nexus S before others.
Google employed a similar tactic for Gingerbread, issuing the 2.3 update to the Nexus One well ahead of other smartphones. It's worth noting, however, that it took a little longer than the promised "few weeks" last time around.
One thing to bear in mind is that although a particular handset is technically capable of running Android 4.0 it is not a given that the carrier or OEM will be in a hurry to issue the upgrade. A general rule to consider is the overall popularity of a model as well as its age. Older phones typically go by the wayside as handset makers and carriers tend to focus on the latest and greatest.