You don't need to chain 2 sed scripts, they could be one, separated by ';'. But even simpler would be piping to tr. For 12.04 without metacity this should be:
for i in $(gconftool-2 --get /apps/compiz-1/general/screen0/options/active_plugins|tr ',' ' '); do echo "# $i:"; gconftool-2 -a /apps/compiz-1/plugins/"$i"/screen0/options | grep "_key\|_button\|trigger_\|initiate\ \|panel_first_menu\|keyboard_focus\|execute_command\|show_launcher" | grep -v "Disabled\|=[[:space:]]*$" | sort; done
However, as Jay_11 already noted, the whole construct seems to show part of what goes into compiz, not the result. E.g. I get
close_window_key = <Alt>F4, but I turned that off. As an avid Emacs user I don't let a window manager get near anything except
<Super>, but this doesn't show!
So the question remains: What is compiz really doing?