Reinstalled Xubuntu today, and none of the above gets system sounds back in 12.04.
Music plays fine, can even enable sounds in gnome-games. Added login-sound to autostart, but just no system sounds (button press etc...).
If anyone has managed this could they please explain how.
This has been an issue i've wrestled with since beta 1 with no joy, and yet in 11.10 they worked fine.