If builds of PostgreSQL 9 are failing and you have version 8.x installed,
you may need to remove the previous version first. See:
  https://github.com/mxcl/homebrew/issues/issue/2510
 
To build plpython against a specific Python, set PYTHON prior to brewing:
  PYTHON=/usr/local/bin/python  brew install postgresql
See:
  http://www.postgresql.org/docs/9.0/static/install-procedure.html
 
 
If this is your first install, create a database with:
    initdb /usr/local/var/postgres
 
If this is your first install, automatically load on login with:
    mkdir -p ~/Library/LaunchAgents
    cp /usr/local/Cellar/postgresql/9.0.3/org.postgresql.postgres.plist ~/Library/LaunchAgents/
    launchctl load -w ~/Library/LaunchAgents/org.postgresql.postgres.plist
 
If this is an upgrade and you already have the org.postgresql.postgres.plist loaded:
    launchctl unload -w ~/Library/LaunchAgents/org.postgresql.postgres.plist
    cp /usr/local/Cellar/postgresql/9.0.3/org.postgresql.postgres.plist ~/Library/LaunchAgents/
    launchctl load -w ~/Library/LaunchAgents/org.postgresql.postgres.plist
 
Or start manually with:
    pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start
 
And stop with:
    pg_ctl -D /usr/local/var/postgres stop -s -m fast
 
If you want to install the postgres gem, including ARCHFLAGS is recommended:
    env ARCHFLAGS="-arch x86_64" gem install pg
 
To install gems without sudo, see the Homebrew wiki.