Since now-ubiquitous LCD displays won't suffer from screen burn-in and start up quickly from DPMS power-off state, the screensavers have become pretty much useless. So they are no longer included in default installations.

However, the EPEL repository https://fedoraproject.org/wiki/EPEL includes xscreensaver, which is a desktop-environment-agnostic screen saver package which has a lot of screensaver modes - so much, in fact, that they have been split into several RPMs: xscreensaver-base, xscreensaver-extras, xscreensaver-gl-base and xscreensaver-gl-extras.

I think KDE4 may even have some integration for xscreensaver, but I'm not sure.