securing Postgres

I need a bit of help getting up to speed on Postgres.

There doesn't seem to be much in the way of documentation for
PostgreSQL's security system.

I've seen various docs
(man pg_passwd, pg_hba.conf and a few references to pg_shadow)

Before I can start playing with this, I want to know it's fairly secure;
how do I assign a password to the postmaster account (pgsql)?

*not* a system password, just something that stops people doing this:

$ dropdb -U pgsql someoneelsesdatabase

Is there a security howto or similar?

Version is 7.1.3.

Thanks!

--
Although golf was originally restricted to wealthy, overweight
Protestants, today it's open to anybody who owns hideous clothing.
-- Dave Barry
Rasputin :: Jack of All Trades - Master of Nuns ::