After installation and setting up users and a default database, psql got me into the terminal, but I couldn't connect from PgAdminIII.
I tried to connect to the localhost with:
psql -h localhostThis failed, because as default, the TCP/IP socket is set to false. The simple fix is to edit the config file and ensure that the port is set to 5432 and the tcpip_socket is set to true.
sudo pico /etc/postgresql/7.4/main/postgresql.conf
port = 5432
tcpip_socket = true