unity program why not available in 11.10

You can't use anymore Ubuntu Classic in 11.10. Now you can use Ubuntu with Unity 3D or 2D, or you can install gnome-shell. You can also use the fallback mode of gnome-shell that looks similar to Ubuntu Classic but it's not it.

For install gnome shell do this:
1. Open a terminal by hitting CTRL + ALT + T
2. Insert and run this command:
sudo apt-get install gnome-shell

For install gnome-fallback-mode do this:
1. Open a terminal by hitting CTRL + ALT + T
2. Insert and run this command:
sudo apt-get install gnome-session-fallback

Then log out and select "GNOME Classic" for the gnome fallback session or "Gnome Shell" for gnome shell at the LightDM login screen.
Remember that you can use other DE, like xfce, lxde or kde.