I know it didn't originate in GNOME, but GNOME was perhaps the most popular environment using virtual desktops at the time that Apple introduced Spaces:
http://en.wikipedia.org/wiki/Spaces_%28software%29#Compariso...
http://en.wikipedia.org/wiki/Spaces_%28software%29#Compariso...
In short, as far as virtual desktops go, what GNOME (metacity/beryl) does is the exactly same thing every window manager has been doing for the past decade at least, and the concept of virtual desktops (non-ICCCM+ implementations) goes much further back than that.
[1] http://standards.freedesktop.org/wm-spec/wm-spec-latest.html