Pg_dumpall

I'm looking for an unattended (cron job) to dump all the databases. We
have both 7.3.3 and 7.0.2 (Cobalt RaQ) to do this for. I cannot grant a
certain user permission to dump the databases in 7.0.2 pg_hba.conf file
and, if I do this for our 7.3.3, does it mean anyone at the command
prompt can access the databases using the '-U' option and it not require
a password? What are most on this list doing for automated dumps?

--
Robert