I am using Ubuntu 11.10, and I have GNOME and KDE desktop environments installed on it. While I am using Unity, I am able to see the shutdown option and able to shutdown the system by clicking that option. But I am unable to find such an option if I am logging in selecting GNOME. In GNOME I have options to log-out and suspend. But this is not what I want. Is there a way similar to that what we have in unity?
Hold down Alt and the Suspend menu item will become Shut Down. You can also just tap the power button on your computer, and a shutdown dialog will appear.
Just so you know, Ubuntu 11.10 is no longer supported and 12.04 has a much-improved version of GNOME Shell - complete with a Shutdown item in the session menu. Upgrading could solve any confusion with this in the future.