How to Install the new Gnome Boxes?
Gnome-boxes cannot be installed on 12.04.
GNOME boxes has not been packaged due to dependency problems. If you want to try out the boxes, try compiling from the source.
For 12.10 and newer it can be installed by simply typing:
sudo apt-get install gnome-boxes
If you are looking to use a newer version, you can consider installing it from the source tarballs.
Do take note that GNOME boxes is still very much in development.
Installation on 12.10:
Click on the button: