Google has made Gingerbread available for NexusOne and if don’t mind waiting a “few weeks” before you receive the “over the air” (OTA) update you probably don’t have to read further. Unfortunately, I have been waiting impatiently for GingerBread update and I can’t wait any further.
At the moment of writing, my NexusOne is rebooting after installing the update (fingers crossed). And jut to be clear, my phone has not been rooted, and what I am going to suggest is not illegal and is not going to void your warranty, whatever is left of it. I have not mentioned Nexus S as I have not tired the steps, but you will find the steps almost similar and other posts for Nexus S.
1. First you need to download the update from the Google server. Download Gingerbread for NexusOne
2. Rename the file. The original file that you download will be named “81304b2de707.signed-passion-GRI40-from-FRG83G.81304b2d.zip”. Rename it to “update.zip”.
Note: If you find the file name to be 81304b2de707.signed-passion-GRI40-from-FRG83G.81304b2d then rename it to update. The extension “.zip” might have been hidden due to the settings on your computer.
3. Copy the file “update.zip” to your Micro-SD card. If you don’t know how to do this, then I would recommend waiting for the OTA update.
4. Shut down your phone.
5. Hold the Volume Down key and then power it back up.
6. Use the Volume key to scroll down to Recovery and then press the Power button.
7. Reboot the phone if it does not do it automatically.
8. You should be getting a screen with a triangle and explanation mark. Press the Volume Up and Power button a few times.
9. Select “Apply sdcard:update.zip” the screen.
10. Watch the droid taking over your phone.
GingerBread appears to be a bit faster, but I actually preferred the old theme. Maybe I will get used to it.
Credit: I followed the steps provided by Geekworld.