pgnotify is a PostgreSQL client-side asynchronous notification handler for Python and PyGreSQL. Typically, asynchronous notification is used to communicate the message "I changed this table, take a look at it to see what's new" from one PostgreSQL client to other interested PostgreSQL clients. A useful programming technique is to generate asynchronous notification in a rule that is triggered by table updates; this way, notification happens automatically when the table is changed and the application programmer can't accidentally forget to do it. At present, pgnotify works with PyGreSQL only. It should work with PoPy and psycopg when those modules provide Pythonic interfaces to additional necessary PostgreSQL client-side functions, as described in the README.