yes, there is also a symbolic link login.wav and logout.wav - are they set/used by a program?
This is of pure interest - googling a bit reveals that canberra-gtk-play uses freedesktop settings - so I'm just wondering where the id "desktop-login" is defined, and what program configures that?
As for sound, I unchecked the gnome-startup sound (that play a .... not pretty... sound after login :-) - and actually prefer a sound/melody when the login-manager is displayed (i.e. before the desktop start). This is setup via GUI btw.