A while ago, we had posted on how you can unlock the bootloader of your Nexus S phone. It was only a matter of time that a method to root the phone was made available. Here’s how you can do so via XDA:
First, reboot into your bootloader/fastboot mode. (Volume + Power Up, or adb reboot bootloader)
fastboot oem unlock
Then, install this recovery:
http://koush.tandtgaming.com/recover…rk-herring.imgfastboot flash recovery recovery-clockwork-herring.img
Then boot into Clockwork recovery and install the Superuser zip file (adb reboot recovery, or from fastboot choose recovery):
To install a rooted/insecure boot image (adb has root):
http://koush.tandtgaming.com//samsun…g/rootboot.imgfastboot flash boot rootboot.img