The folks at XDA have always done it and they have come with another root, this time for the Samsung / Google Nexus S. They have found the Nexus S root within a day of its availability in the stores. Last day, that is, December 16, it was made available to buy in US through Best Buy stores and now the Nexus S rooting method has been brought out by the XDA developers.
Below are the instructions to root Nexus S on Android 2.3 Gingerbread.
First, reboot into your bootloader/fastboot mode. (Volume + Power Up, or adb reboot bootloader)
fastboot oem unlock
Then, install this recovery:
fastboot 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, THIS IS OPTIONAL, THE ABOVE STEPS ALREADY GOT YOU ROOT):
fastboot flash boot rootboot.img
If you are having any doubts or difficulties in rooting Nexus S, then slide to this page for more info.