Installing it on a Debian Linux box is really easy, lets see how to do it.
Modifying the apt sources
You may use your favorite text editor, mine is vim
Then be sure to add this line.
# Looking Glass Repository deb http://javadesktop.org/lg3d/debian stable contrib
Getting the software
sudo apt-get install lg3d-core
It will download all the needed packages, grab a cup of tea, as it will take sometime depending on your internet connection.
Once downloaded it will start the installation, you will need to accept the Java and Looking Glass agreements, and it is done!
Now log out, and log in again, but this time selecting Looking Glass as your Default Desktop.
As you can see from the screenshot above, it has really good and nice effects, I think it will work better for nVidia cards, as I have read that they perform better than ATI on Linux.
This instructions should also work for Ubuntu, but I have not yet tested them.
Check out this Youtube video.