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