Shutting down from the sidebar
To me, the sidebar was an odd feature of Vista. It reminded of the old Office
toolbar(which I never used), yet as time passes it is starting to grow on me
mainly to the useful gadgets people build for it.
One such useful gadget is the Control System gadget that allows you to
shut down(including all iterations:standby,hibernate etc.) your system from
the sidebar:
Download it here.