PGQ of Postgresql
PGQ is the queueing solution from Skytools. The Londiste replication solution is a consumer daemon built on PGQ, and the API is accessible for you to create any asynchronous processing facility, based on queuing.
PGQ will solve asynchronous batch processing of live transactions.
That means you're doing some INSERT/DELETE/UPDATE of rows from your live environment, and you want to trigger some actions but not at COMMIT time, later on. Not in a too distant future either, just asynchronously: without blocking the live transaction.
Every application of a certain size will need to postpone some processing at a later date, and PGQ is a generic high-performance solution built for PostgreSQL that allows implementing just that: the batch processing. PGQ will care about the asynchronous consuming of events, the error management, the queuing behaviour, etc, and it comes with a plain SQL API to do this.
The API documentation is online, this document will consider you know about it.