Google Nexus S 4G reportedly will soon enjoy the Android 4.0 Ice Cream Sandwich. This upgrade will bring improved performance WiMAX of Android 2.3.
This upgrade is almost identical to the Nexus S upgrade to the regular version, except on its 4G speeds. There is also an Android Beam transfer using NFC and Face Unlock.
Android 4.0 brought significant changes to the interface and some speed improvements and support new applications such as Chrome for Android. Not yet certain when this upgrade will be officially rolled, but indications show via OTA upgrade will come in the next few weeks.