Installing majority of softwares on Ubutu is just a like away same is the case with PostgreSQL
Installing PostgreSQL (8.3)
$ sudo apt-get install postgresql
Setting the password for the postgres user
$ sudo -u postgres psql template1
ALTER USER postgres WITH PASSWORD 'password-u-need';
\q
this installs and configues the password for the postgreSQL
is this not easy with ubuntu
and yes if you need to use postgreSQL with PHP on your apache server the install the php5-pgsql module using the following
$ sudo apt-get install php5-pgsql