This is an update of my other login mockup ([link]
BTW, just to make sure you know what everything is:
The top panel displays stuff like volume and shutdown buttons
There is a 'ribbon' with the user selected and an image on the left
Underneath is another ribbon with the selected desktop
On the right is a clock, and a ribbon for the password
The last ribbon is for the guest user - more ribbons will be displayed for more users and can be scrolled through.
That was just to give you an idea of how I intend this to work - it is only a mockup though.