As it comes from project’s site Zim is a WYSIWYG (What You See Is What You Get) text editor written in Gtk2-Perl that brings wiki concepts to your desktop (every page is saved in wiki format). Nice hint is that pages can contain links to other pages (to create file it’s enough to link to non-existent one). Pages are ordered in a hierarchical structure that helps you to keep track of TODO lists or to serve as a personal scratch book.
Latest version of Zim is 0.22 but it’s included into many Linux distributions’ repositories (sudo apt-get install zim -y works in Ubuntu as well). Packages for ArchLinux, Mandriva, Suse and others are here. It’s also possible to get it working with Windows.
Zim is nice, I am constantly looking for information on how to run it on Windows, but there is almost nothing.
The link you point to is broken.
Another is http://dewarim.de/wms/programme/installing_zim.html but it states that it is not possible to run Zim on Win so far.
@Riccardo: Try this for running Zim in Windows:
http://code.google.com/p/zimdesktopwiki-windows/