Ximian is a different desktop based on GNOME, Miguel de Icaza, one of the co founders of th GNOME Foundation is now vice president of developer platform at novell.
Ximian was the name of the company that Icaza co-founded and Novell bought.
You are correct that owning GNOME is not the correct terms.
GNOME is handled by the GNOME Foundation. Novell owns Zimian, the desktop and the company including other products that Ximian owned.
Exciting times for Novell.