Is this correct command to shutdown Leopard after 60min?
sudo shutdown -h 60
The correct usage from the command line for shutting down Mac OS after 60 minutes is:
That is not the method that Apple recommends using, though it is probably the best way on a headless server. (Update: See comment and link from @radius - the use of shutdown is recommended by Apple's server CLI admin guide). From the Command Line Junkies Guide to Mac OS X (the site is out of date but the reference to using osascript is current):