It may be a bit late to the party, but the Android 4.1 updates for the Nexus S and Galaxy Nexus on Sprint are finally available. The Android 4.1 update includes Google Now, Project Butter, offline voice dictation, improved camera and Enhanced Notifications. Be sure to check out our Andoid 4.1 overview for more details.
Keep in mind that installing Android 4.1 on your Galaxy Nexus or Nexus S means you will officially lose support for Adobe Flash. The update will not uninstall Flash from your device, but you may experience some performance issues.
If you have not yet received an update notification on your Sprint Galaxy Nexus or Nexus S, you can try to manually ping the servers by going to Applications > Settings > About Phone > System updates > Check. Let us know how the update goes and which new features you enjoy the most.