My guess is, that is a custom login screen. There are plenty of apps out there that will allow you to use a custom screen, or just change the wallpaper behind them. I believe we even have a customization subforum here, too.
By the way, I know you are new here, but people aren't going to appreciate a thread being bumped, especially after only being posted for three hours. Have some patience. There are good people answering questions here (for free).