If you want to run a GNOME session, without notify-usd (using the old daemon, notification-daemon) install and use gnome-stracciatella-session. That'll start (selectable from gdm login) a GNOME-session without Ubuntu-specific components.
If you want to run a GNOME session, without notify-usd (using the old daemon, notification- daemon) install and use gnome-stracciat ella-session. That'll start (selectable from gdm login) a GNOME-session without Ubuntu-specific components.