I hesitate to go down this road, but what features do you think originated in GNOME and found their way into OSX? I think you're giving quite a bit of credit where it is not due.
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