New install - can't access pgsql

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.