when I zoom out and have a full view of my cosmos, I see empty space beyond it until I zoom out large enough to see the eagle. Could you connect other cosmos running on another computer over typical TCP/IP (ssh/ssl encrypted)? Imagine how brilliant that would be combined with the previous suggestion (vnc/rdp/x11 server)?
But it would become very difficult if you want to make it possible to copy and move things around. There I think the best solution is still to mount network file systems.
The current toolset I use with my typical 2D guis (linux X11/compiz, windows Vista/Aero, mac Leopard/X11) is called "synergy". It auto-magically copies the "copy/paste" buffers but that's it. Righting a rsync over SSL front end as a ZUI VcItem wouldn't be too complex, since rsync is already cross platform, but that could be another option.