I installed PostgreSQL using Homebrew on Lion. It starts okay but wouldn't shutdown. I tried:
$ #started with
$ pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start
$ #tried stoping with
$ pg_ctl -D /usr/local/var/postgres stop -m immediate
waiting for server to shut down................................... failed
pg_ctl: server does not shut down
I fixed this issue by deleting the Launch Agent:
launchctl unload -w ~/Library/LaunchAgents/org.postgresql.postgres.plist
rm ~/Library/LaunchAgents/org.postgresql.postgres.plist