New install - can't access pgsql

[Richard Doust <rdoust@xxxxxxx>]

I have just done a new compile and install of postgresql 8.1.0 on a  
Mac running OS X 10.4.3 Server. This machine hosted a postgres  
database in a production web application environment until recently  
when I moved the application and the database to a different host on  
the network. My intent is to use the old host as a development  
platform. After moving the database to the new host (no problems,  
compiled and installed 8.1.0 on a Mac running OS X 10.4.3 client,  
backed up and restored the database), I found that I couldn't access  
postgres on the old host any longer. When I tried, logged in as  
postgres, the dbms user who had always in the past been able to, I  
got this error:
psql: FATAL:  No pg_hba.conf entry for host localhost, user postgres,  
database postgres
I had been running 8.0.1 or some such, so I decided to compile 8.1.0  
on the old host and deploy it and try again. Before running make  
install, I deleted /usr/local/pgsql and all of its subdirectories as  
root. Then I ran make install. I then ran ititdb successfully, then  
try to create a database using createdb and get the same error:
psql: FATAL:  No pg_hba.conf entry for host localhost, user postgres,  
database postgres
Of course, the pg_hba.conf file is in the $PGDATA directory, and does  
specify the defaults, which should allow postgres to access the  
postgres database on localhost.
Is it perhaps looking elsewhere for pg_hba.conf? If so, how can I  
find out? I'm sure this must be incredibly easy, but it's annoying me  
at this point?
Thanks for any help.