Or just use Konsole with its “send input to all windows” feature.

There are a few reasons:
* This script actually make sure that a server was shutdown by pinging it. It will also elegantly skip hosts that are already down.
* Its automated – of course it is limited to just doing a shutdown, but it does this automatically with a single command – no need to run a full application with UI and everything. It will do its job cleanly and report the results in a simple way.
* It does not require X – you can run it from a VT or from a putty console on windows or anything
* I like writing scripts 😉