$rm -rf /usr/local/var/postgres # install the binary
$ brew install postgresql
# init it
$ initdb /usr/local/var/postgres
# start the postgres server
$ postgres -D /usr/local/var/postgres
# create your database
$ createdb mydb
# Access db.
$ psql mydb
psql (9.0.1)
Type "help" for help.
On error, first update:
brew update
brew upgrade