You can download it from Google and manually install it now.To install the latest Nexus S build GRH78C, follow these steps:
Step 1: Download the official Android 2.3.2 update for Nexus S.
Step 2: Copy this file to the root of your SD card. (Nexus S users no longer need to change the file name to update.zip)
Step 3: Now power off your phone, hold down the “Volume Up” button, followed by the “Power” button to turn it back on.
Step 4: Now use the volume rocker buttons to navigate to “Recovery” option and then select it using “Power” button.
Step 5: Now when you see an exclamation mark –like image on the screen, hold down the “Power” button followed by “Volume Up” button.
Step 6: At this stage you should be presented with Android’s Recovery menu. Now select the option to apply the update from SD card, followed by selecting the actual update “.zip” file using the “Power” button.
Step 7: Find the update file (GRH78C-from-GRH78) on your sdcard and then press the POWER button to flash it.
Step 8: Wait for the update to complete and then select “reboot system now”.
That’s all.
Nexus S GRH78 update to GRH78C :
http://android.clients.google.com/packages/ota/google_crespo/353e267378cd.signed-soju-GRH78C-from-GRH78.353e2673.zip
Nexus One FRG83D update to FRG83G:
http://android.clients.google.com/packages/ota/passion/2854b06b22b9.signed-passion-FRG83G-from-FRG83D.2854b06b.zip