If you remember the screen-shot on the right than you used to add host aliases, set your host name etc. from Ubuntu Hardys menu System --> Administration --> Network.
After upgrading to Ubuntu 8.10 (Intrepid) this menu was gone, and the options can't be found anywhere.
Install instructions
sudo aptitude install gnome-network-admin
After this instruction the menu entry returned and you can tweak your network as usual.
