Some time ago I found that pretty ubuntu notifications are available as a package notify-osd in ArchLinux. I installed and tested it. The question is how to enable notifications running by default in ubuntu (volume up/dpwn, backlight, some programs notifications, etc)? I'm using XMonad WM instead of desktop environment.
According to the Arch Wiki, notify-osd replaces notification daemon. So you will need applications which use this. Many applications, such as Pidgin, can be made to support it using plugins, configuration, or build options. For the volume, backlight, etc, things will be more difficult. These are probably provided in Ubuntu by Gnome. You will need to find some notification daemon-supporting software to replicate all of this functionality.