I have encountered an error at the first step of installation using PG4WP.
The message I had was that login info were correct but the database could not be selected.
Config : PostGreSQL 9.1.2 ; PG4WP 1.3.0 ; PHP 5.1.3-RC4
I solved this by manually editing pg4wp/driver_pgsql.php
line 80 :
return wpsql_select_db( 'template1');
I replaced template1 by my database name and the problem was solved.
PS : my blog is hosted on a subdomain of free.fr