Ok folks, the official Android 2.3.6 Gingerbread update for the HTC-made Google Nexus One handset is now live and ready to be downloaded. The update has begun rolling out as an OTA update. Make sure to keep checking for the update, you should be able to get yours too. There is also a way to manually install the Android 2.3.6 update right now for Nexus One instead of waiting for the roll out that’s presently in progress. If you prefer the regular OTA update process, the Nexus One owners should press Menu > Settings > About Phone > System Updates to get their 2.3.6 Gingerbread now. Carrying the build number GRK39F, the Android 2.3.6 Gingerbread update for Nexus One will bring important bug fixes and various security patches. As a refresh, Google Nexus S got the Android 2.3.6 Gingerbread update for fixing the voice search bug in early September.
Download: Android 2.3.6 Gingerbread for Nexus One (hit the link).
Follow the following instruction to install the Android 2.3.6 Gingerbread on your Nexus One handset.
# Download the file from the above “Download” link.
# Rename the downloaded file as “update.zip” (remove quotes) or rename it as “update”, if you are running a Windows PC machine.
# Copy that file, update.zip or update, and put it on your microSD card.
# Make sure your Nexus One is off. Now, hold down the trackball and press the power button together.
# You will now see a white screen and the Android bots. Select Bootloader –> hit Recovery button.
# Handset reboots and you will see an Android icon as well as a triangle with an exclamation (!) point inside it.
# Now press the volume up and power button at the same time.
# With the help of the the trackball, you should choose “Apply sdcard:update.zip” or “Apply sdcard:update”.
# Follow the onscreen instructions now and let the process to finish.
# Done. Your Android 2.3.6 Gingerbread piece of cake is ready now.
Source: Google