Alright, Nexus S 4G owners, it's your turn. After waiting on the GSM Nexus S and Galaxy Nexus phones, then the WiFi version of the Motorola XOOM, the CDMA Nexus S is getting its time in the sun with an official Ice Cream Sandwich rollout. If you're still using the stock Gingerbread ROM, check your Settings menu to see if it's rolling out to your region at the moment - the carrier says that it will begin sending out the updates this afternoon.
Nexus S GSM owners got an early looks at Ice Cream Sandwich back in December, but it was yanked almost immediately for further testing. All the current Nexus-class devices were updated to the latest version (4.0.4) of Android last week. The CDMA devices... weren't. The Nexus S 4G is the first among them to get the update, but Verizon customers who bought a XOOM or Galaxy Nexus LTE are still waiting. CDMA XOOM owners have the most to be upset about, since they're still rocking Honeycomb, assuming that they've stayed on the official software releases.
Why the delay? Google has decided not to support CDMA phones or tablets at the same level that they do for GSM and WiFi, owing to a quirk in the way that CDMA devices are authenticated on the network. When using CDMA a phone or tablet needs a unique software key that's different for every carrier, and by its very nature cannot be open source. Therefore the CDMA Galaxy Nexus and XOOM were taken off the list of official developer devices... notably after most of the first round of early adopters got a chance to put down their hard-earned cash. Want to know when your Verizon Galaxy Nexus or XOOM will be updated? In the words of the Dread Pirate Roberts, get used to disappointment.