[Nexus S Q&A, Help & Troubleshooting] Supraz01:
I "attempted" to root my NS following these directions:

I. Before You Begin

1. This will unlock your phone’s bootloader (so you can flash recoveries and ROMs), and can be undone very easily (unlike the Nexus One).

2. This WILL ERASE all your information on the phone.

II. Setup ADB

1. Head to our How To Setup ADB procedure, once you can see your phone’s serial number after typing adb devices then come back to this procedure and continue.

(MAKE SURE YOU FOLLOW ALL THE STEPS IN THE WRITTEN PROCEDURE AS THERE HAVE BEEN UPDATES ADDED).

III. Unlock the Bootloader

1. Turn off your phone.

2. Turn it on by holding Volume Up and Power until fastboot mode comes up.

3. Plug the phone in via USB cable to your computer while it is in fastboot mode.

4. Open a command prompt on your computer by clicking on the Start menu button and typing cmd and hitting enter in the search box.

5. In the command prompt that pops up, type the following with hitting enter at the end of each line:

cd c:\androidsdk\tools\

fastboot oem unlock

6. At this point the phone will ask you to confirm, select yes. You now have an unlocked bootloader.

IV. Flash a Custom Recovery Image

1. Download the custom recovery image and save it to your computer:

ClockworkMod Recovery for Nexus S

2. Copy the recovery.img file inside the tools folder of the sdk (so it is in the same folder as fastboot.exe)

3. Then in the command prompt that should still be open, type the following with hitting enter at the end of each line:

fastboot flash recovery recovery.img

4. Once it is flashed, leave the phone in plugged in and in fastboot mode.

V. Root the Phone

1. In fastboot mode, select Recovery using the volume buttons and power button and wait for it to boot into recovery mode.

2. Download the Superuser flashable zip file and save it to your computer.

Superuser for Android 2.0 and Up Flashable Zip

3. Once in recovery mode, select Mounts and Storage then select Mount USB Storage so we can transfer files to the sd while it is in recovery mode.

4. Copy the Superuser.zip file to the root of your internal storage (do NOT extract it, do NOT put it in any folders, just on the phone’s storage itself).

5. Select Unmount on the phone.

6. Select Mount System, then select Go Back to get back to the main menu.

7. Then scroll to flash zip from sdcard and then choose zip from sd card and select the superuser.zip file and wait for it to finish flashing.

8. Once it is done, select Go Back then Reboot System and wait for the phone to reboot.

VI. Stop the Phone from Uninstalling the Custom Recovery Image

1. Once the phone is booted up, plug it in via USB cable and do NOT mount the storage.

2. Open a command prompt on the computer and type the following with hitting enter at the end of each line:

adb shell

cd etc

mount -o rw,remount /dev/block/mtdblock3 /system

mv install-recovery.sh install-recovery-no.sh

3. That will mount the system as writable and rename the file that overwrites the recovery image on reboot so that our custom recovery will stay.

4. Turn off the phone and turn it back on by holding down Volume Up and Power to get into fastboot mode.

5. Plug the phone in via USB cable while in fastboot mode and open the command prompt again and type the following with hitting enter at the end of each line:

cd\

cd c:\androidsdk\tools\

adb reboot bootloader

fastboot flash recovery recovery.img

5. Once it is done, you have just reflashed the recovery image and it will now stick. You are all done! You have an unlocked bootloader, a custom recovery image, and root access! If you want to now load a custom ROM head to the next procedure linked below.

I ran into an issue near the end with this step under VI:

2. Open a command prompt on the computer and type the following with hitting enter at the end of each line:

adb shell

cd etc

mount -o rw,remount /dev/block/mtdblock3 /system

mv install-recovery.sh install-recovery-no.sh

I used root explorer to mount and rename the file since I couldnt get it to mount with adb shell. My issue now is that when I boot into fastboot mode and go to recovery, I get the error icon (The android with the triangle with the ! in the middle). I cant for the life of me figure out how to get recovery back. It also does not recognize my device in fastboot mode with adb devices but does recognize it when its booted into the regular os. Any ideas?

This is solved. Apparently the directions are a little sketchy.

When it got to this step:

5. Plug the phone in via USB cable while in fastboot mode and open the command prompt again and type the following with hitting enter at the end of each line:

cd\

cd c:\androidsdk\tools\

adb reboot bootloader

fastboot flash recovery recovery.img

the adb reboot bootloader command would not work. Skipping it solved my problem.