Right after installing / upgrading to Fedora 15, you may not find option to power off, if your computer supports suspend.
You can still get shutdown option by…
Click on Right Top (User Name)
Press ALT Key
Suspend will change to Shutdown.
If you prefer to add shutdown permanently.
yum install gnome-shell-extensions-alternative-status-menu -y
Once package is installed you may need to reboot to get Power off option along with hibernate / suspend.
