With all the excitement of Nexus availability and the Android 4.2 source code being pushed into AOSP this morning, one little statement by Android developer JBQ regarding 4.2 device support in the AOSP announcement was easy to overlook.
Yep, that (very, very likely - it's intentionally vague) means exactly what you think it does: it's the end of the road for software updates on the Nexus S and Motorola XOOM (and yes, that means all variants). At least, that's what's implied. When asked for comment, JBQ said no further information could be given about future updates for the Nexus S or XOOM, which is the standard response to such inquiries.
So, the devices will quite probably be left at Android 4.1.2, and receive no further support in AOSP. Of course, the developer community will continue to vigorously support these two products for a while yet, so don't get too down if you were absolutely dying for that bump to 4.2 on your Nexus S. CyanogenMod and various other ROMs will probably continue to develop for these devices until doing so becomes little more than a game of "will it run?"
Based on Google's previous end-of-life policy (... for one phone) on Nexus hardware, the Nexus S and XOOM fared about average. The Nexus S survived all the way to fall 2012 (with the release of 4.1.2), a full 22 months and two major updates to Android (4.0, 4.1). The XOOM managed to make it through Honeycomb (with several smaller revisions to that release), ICS, and up to Jelly Bean, also accounting for two major updates. If you don't recall, the Nexus One was supported up to Android 2.3, and started at Android 2.1, which yet again made for two major updates.
It's sad to see support for these two Google Experience devices end, though we can't say the writing wasn't on the wall. The question to ask now, though, is will the Galaxy Nexus make it beyond Android 4.2? I guess we'll see next summer.