> Settings > Application > Development >
Then create this if using OpenSuSE (not required for Ubuntu 12.04)
# cat /etc/udev/rules.d/53-android.rules
SUBSYSTEM=="usb", ATTRS{idVendor}=="04e8", MODE="0666"
note the vendor id is the one from Samsung (see http://developer.android.com/tools/device.html#VendorIds).
Now under OpenSuSE 11.x restart udev
# /etc/init.d/boot.udev restart
then plug the usb cable in the phone and as regular user you should see the device now
~/android-sdk-linux/platform-tools> adb devices
* daemon not running. starting it now on port 5037 *
* daemon started successfully *
List of devices attached
304D19AFD0235C8E device
and start the sehll
~/android-sdk-linux/platform-tools> adb -d shell
$ pwd
/