What's wrong with this identification configuration?

This is the idenfication setup in my /var/lib/pgsql/data/pg_hba.conf

local all trust
host all 127.0.0.1 255.255.255.255 trust

This is supposed to authenticate any user to be able to access my postgresql
system any time, no?

But this is what happened:

[root(at)Monet wweng]# su postgres
bash-2.05a$ psql template1
psql: FATAL 1: No pg_hba.conf entry for host localhost, user postgres,
database template1

bash-2.05a$ exit
[root(at)Monet wweng]# psql template1
psql: FATAL 1: No pg_hba.conf entry for host localhost, user root, database
template1

[root(at)Monet wweng]# exit
[wweng(at)Monet wweng]$ psql template1
psql: FATAL 1: No pg_hba.conf entry for host localhost, user wweng, database
template1

Why is this happening? And how can I log in the template1 database?

I am using postgresql 7.2.3 on Redhat 7.3.

bash-2.05a$ rpm -qa | grep postgresql
postgresql-7.2.3-5.73
postgresql-libs-7.2.3-5.73
postgresql-server-7.2.3-5.73
postgresql-devel-7.2.3-5.73

Thanks a lot!

Wei