Nexus S won't need to be updated through Samsung's desktop software Kies, and instead it will get the updates directly over the air. That isn't that surprising considering this is a phone made with Google's help. Since it has stock Android, Google will update it themselves.
The news is confirmed by Android developer and Android programming book author Reto Meier, who says Nexus S will get updates in the same way as Nexus One has gotten them so far.
Via - Slashgear