Debian Enterprise Linux login screen. Of course, there is no Debian Enterprise Linux, this is a pun of Redhat Enterprise Linux, just like my Ubuntu Enterprise Linux themes before. Basically the Redhat Enterprise Linux screen with Debian's theme colors.
If you'd like to use the GDM background as your wallpaper, just add the background.png image in the DebianE GDM theme folder to your wallpaper list.
Look for the matching Gnome-Splash screen to go with this.