haha that looks nothing like it! thats just a mockup that some idiot thought the login screen would look like after seeing leopard at wwdc07. why would anyone develop a window that transparent.... pfffh stupid
ive seen the login screen in a screenshot that someone posted in another mac forum. unfortunately i cant remember where it was and i now cant find it!.... lost forever in the internets!
but from what i remember the login window is just like tiger's but with the new unified UI and the background is the purple space aura that leopard uses as default in the final version. just like tiger uses aqua blue as default for the desktop and login window. but i cant remember if the apple logo has changed or not.