I don't know what I would like; I'm happy the current way. As long as the songs are good (which is subjective, true), we can add them. And even better, we can submit them upstream.
I slightly disagree. I believe the login sounds (along with wallpaper) should be unique to the distro. It helps in easy identification of the distro. I remember seeing some video interview where Miguel correctly spots a Windows-XP login sound, Intel's music is also unique. We should have some kind of unique music which upstream will probably not care much about, as every distro will want their own login sound, theme, wallpapers. (yes gnome3 first release will be an exception)