Most UPS’ come with a serial port, usb or network connector and some sort of free software agent. This software agent can be installed on your servers and when the UPS detects a power outage you can configure the software to shutdown your server gracefully after a pre-determined amount of time.
All to often this software is completely left out of the loop in a server configuration or even still the administrator forgets to even connect the UPS monitoring cable to the server. This is just sloppy work in my opinion and it really should be done.
Some administrators have mentioned that they don’t configure UPS shutdown because with virtualization they have no idea how to configure this. If you go to the VMware communities you can find many scripts that show you how to configure UPS shutdown in a virtual environment.