Still it is running in first month after its launch, Google Nexus S has begun getting its first Over-The-Air(OTA) update process, which brings Google Maps updates and fixes some bugs. According to some sources, not every handset is getting this first software update yet, but still you can do some tricks to get the update notifications just by dialing *#*#checkin#*#* from your Nexus S handset.
The latest update codenamed as build GRH78 and the Nexus system info now shows Android 2.3.1. As with all OTA updates, it may take some time for you to be pushed the download. It seems browser lag & blurry MMs appearing to be fixed with this OTA update and it is weighing 1.9MB of size only.
Refer this post for Nexus S Full technical Specifications.
Source: Android Community