Ximian produce a "Distribution" of GNOME called, co-incidentally, "Ximian GNOME".
Ximian spend a lot of time making GNOME look pretty, by working on good themes, and also cleaning up applications to make them workable and useful. If an application doesn't exist that they think should, they write it, for example the Evolution mail client.
Most ditributions of linux use XimianGnome?, notably, Debian doesn't for some reason.
Note: the new versions are called XimianDesktop. Please go see that page.
No other page links to XimianGnome yet.
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