Zoetrope

###########################################################
# A startup item has been generated that will aid in
# starting postgresql83-server with launchd. It is disabled
# by default. Execute the following command to start it,
# and to cause it to launch at startup:
#
# sudo launchctl load -w /Library/LaunchDaemons/org.macports.postgresql83-server.plist
###########################################################
--->  Installing postgresql83-server 8.3.1_0

To create a database instance, after install do
 sudo mkdir -p /opt/local/var/db/postgresql83/defaultdb
 sudo chown postgres:postgres /opt/local/var/db/postgresql83/defaultdb
 sudo su postgres -c '/opt/local/lib/postgresql83/bin/initdb -D /opt/local/var/db/postgresql83/defaultdb'

To tweak your DBMS, consider increasing kern.sysv.shmmax by adding an increased kern.sysv.shmmax .. to /etc/sysctl.conf

A little tip for us anal-retentive PostgreSQL users who rely on macports to install PostgreSQL into their Mac OS X systems.

sudo defaults write /Library/Preferences/com.apple.loginwindow HiddenUsersList -array-add postgres

So you don't see that nasty little database user popping up in your LoginWindow to confuse you. More in this Macworld article.