I wrote about how to get rid of the “Suspend” option from gnome’s system menu on RHEL/SL/CentOS-5 in my earlier blog. On RHEL-6, “Suspend” and “Hibernate” are now found under “Shutdown” in the “System” menu in gnome.
To remove these options from the list of available actions, create a PolicyKit file named 10-disable-suspend-hibernate.pkla (for example) with the following contents:
[Disable suspend] Identity=unix-group:* Action=org.freedesktop.devicekit.power.suspend;org.freedesktop.devicekit.power.hibernate ResultAny=no ResultInactive=no ResultActive=no
and save it in the /var/lib/polkit-1/localauthority/50-local.d directory.