man vim, "FILES:" section says: /usr/share/vim/vimrc System wide Vim initializations. but it seems that file is not used anymore (maybe the same is true for /usr/share/vim/gvimrc but I can't test it), in fact: :version says something different: system vimrc file: "/usr/share/vim/vim57/macros/vimrc" rh6.1 used system vimrc file: "$VIM/vimrc" and on my system it refers to /usr/share/vim/vimrc
I've fixed the man page in 5.7-4. We've decided to move vimrc to the version-specific directory because vim 6.0 needs slightly different options than 5.7.