Google is rolling out the latest version of Android, Android 4.04 Ice Cream Sandwich for the to UMTS/GSM Nexus S, Xoom Wi-Fi, and HSPA+ Galaxy Nexus devices.
Google will be pushing out more updates in the "coming weeks."
The update existing Ice Cream Sandwich Android users offers stability improvements, better camera performance, smoother screen rotation, improved phone number recognition and more.
The only Galaxy Nexus supported is the world unlocked version in this country, the Verizon Samsung Galaxy Nexus is not getting an update, yet.
The pure Google devices are getting the update first because the software doesn't have to go through carrier testing and enhancements.
Android 4.0 Ice Cream Sandwich added some features such as Android Beam, Face Unlock, a new UI and improved camera (see all features and video). It combined Android 3.2 Honeycomb features and updates other features.