Root! Is a prominent word in the Android Community that can trigger glee or angst with Motorola's eFuse system in place on the Droid X. But for those who own a Vibrant variation of the Galaxy S, root is available for you!
In comparison with other Android devices, this method is very simple and painless which is surprising for a device that has a custom UI on top of Android. But is has been said that TouchWiz isn't heavily intertwined within Android, so it is probably why it's as simple as drag and drop.
Follow this link: Download Link for update.zip and you will copy that file and name it as (update.zip) nothing more and nothing less done to the file and you will put it in the internal storage of the phone, boot into recovery mode, and install the update and you're done! So simple! But don't worry, we have more detailed instructions for you to make sure that you have a better understanding of how to obtain root. If you brick your device somehow or for any reason, that is your responsibility and not ours or the people who found out how to root the Vibrant. Proceed at your own risk.
Rooting the T-Mobile Samsung Vibrant (Galaxy S variation):
-Download the file above and make sure it's named: update.zip
-On your device, head to Settings, Applications, USB settings and select Mass Storage
-Connect your device to your computer and select mount from the notification drop down bar
-Copy the update.zip file into the INTERNAL storage (not the SD card with Avatar)
-Turn your device off
-Press and hold volume up and volume down while powering on the phone and this should get you into a recovery menu (this might take a couple of attempts to get the combination right)
-Once in recovery mode, select Reinstall Packages (use volume down to and then power button to select)
The phone should then reboot and you will have:
And there you have it, you have obtained root access on your Vibrant Galaxy S phone! And in case that you want to unroot...
The following commands must be typed in terminal on the device by using ADB shell:
rm -r /system/app/Superuser.apk
rm -r /system/xbin/busybox
rm -r /system/bin/su
And that's it folks, that's how you can obtain root access and unroot. For more information regarding this procedure, you can head over to XDA Forums using this link: http://forum.xda-developers.com/showpost.php?p=7150299