Does Ubuntu-GNOME 13.04 Contain Gnome Classic Session?
Solution 1:
Ubuntu GNOME 13.04 won't have Gnome Classic (gnome-session-fallback) preinstalled. But you will be able to install Gnome Classic using:
sudo apt-get install gnome-session-fallback
It will ship with GNOME Shell 3.6 only.
Solution 2:
Ubuntu 13.04 will only have Unity included. As for Gnome Classic, its maintenance has been dropped by the Gnome Foundation, but you may be able to use the new Classic Mode in future releases of Ubuntu Gnome. The new Classic Mode will be available in Gnome 3.8.