I was not really happy with the current GNOME lock screen dialog (top). It seemed to waste a lot of space and the stark black background was a bit…well…stark 
So I tried to redesign the dialog itself so it didn’t waste as much space and then added a background and a drop shadow to make it integrate a bit better with the current desktop.
The wallpapers used are ‘Relax’ by ~Big-sb (http://bit.ly/bokjQS) (middle) and the Ubuntu Maverick wallpaper (bottom).
Any comments?
Yeah, looks neater, maybe suggest this upstream
I like your design better than the standard Gnome lock screen. Maybe it can incorporate the wallpaper of the current user or the wallpaper from GDM.
Where is tutorial?
Since this is currently just a mockup, there is no tutorial yet. However if I do manage to implement this, I shall post a tutorial on my blog (here).