GNOME Clipboard Daemon is a program that keeps the content of your X clipboard in memory, so the clipboard won' get lost even after you close the application you copied from. It's a daemon - it has no GUI. You start it and it'll run in the background and Just Work(tm).
Created attachment 71302 [details] gnome-clipboard-daemon-1.0.ebuild
*** This bug has been marked as a duplicate of 39299 ***