I find the .Mac screensaver really annoying and wanted to take it out of my screen saver list, because I use the "Random" screensaver and don't want it in my randomise list.
Problem: I couldn't find the screensaver on the hard drive. I searched the entire hard drive and came up blank.
Explanation and solution: The screensaver is called .Mac.slideSaver and it resides in /System -> Library -> Screen Savers/ ... but the "dot filename" of the screen saver hides it in the Finder! So off to the terminal we go! Tally ho - eh what! Just use the terminal to rename it with:
% cd /System/Library/Screen\ Savers/And you are done. ;)
% sudo mv .Mac.slideSaver .Mac.go_away
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020930062052528