LISTEN and NOTIFY are a great feature. We used them heavily in one system I worked on. As the project evolved though, we decided the best way to use them was to

LISTEN and NOTIFY are a great feature. We used them heavily in one system I worked on. As the project evolved though, we decided the best way to use them was to have clients to both our main message brokers and the postgres server, and translate between them. Largely this was to avoid overloading the pg server as a message broker also -- particularly because for our uses dbus was a much better alternative for local system message passing. Now that NOTIFYs officially have payload support, YMMV.