This is a LightDM theme for the Webkit greeter which tries to imitate the look and feel of the Mac OSX lion login screen
http://www.youtube.com/watch?v=1Frf3QlZ_gw
You will need LightDM as your login manager. On newer versions of Ubuntu this is already the default. Additionally you will require the webkit greeter. This is done by executing the following command in the command line:
sudo apt-get install lightdm-webkit-greeter
Once the installation finishes, you need to make the webkit greeter the default greeter. This is done by editing the lightdm configuration under:
/etc/lightdm/lightdm.conf
and changing the greeter-session value to lightdm-webkit-greeter. My lightdm.conf looks like:
[SeatDefaults] greeter-session=lightdm-webkit-greeter allow-guest=false .
The second step is to install the actual theme. This is done by copying the files of this repository into the following location:
/usr/share/lightdm-webkit/themes/mac
Finally, change the /etc/lightdm/lightdm-webkit-greeter.conf file to contain the following line:
webkit-theme=mac
Now you can reboot and enjoy the new theme.