there's a program named like 'login manager' in the 'desktop' menu. get there you would find the button titled 'install login screen'

@ jannone:
I noticed the icon-thing, too. Unfortunately I'm not good in creating icons (these were my first) and this was already the best I could do. If you have an idea for a good replacement let me know.

very cool I'd like more rounded icons tho... The one in the middle looks very unfitting

Thanks for the tip. I'm actually not that much into graphic design and just keep playing around with Gimp or Inkscape until I get a somewhat good looking result. Anyway, I'll try to add the border and if I manage to get something better looking I'll update it.
Glad you like it anyway.

I like this, but one thing about the whole gloss effect - normally I'd inset the gloss part (layer?) because it gives the box with the effect applied to it more depth and looks like a big chunk of glossy shiny stuff.

Basically the gloss part should be moved inwards so as to give the impression of a border around the outside of the box. Inset it from the top, left and right by about (rough guess) maybe 5px, experiment with it see what you like. Looks really nice though, and great for minimalist desktop freaks like myself.