Point-in-time recovery or PITR is one of my favorite PostgreSQL features. Most database servers have a transaction log for recovery. (MySQL is one of the few exceptions; more on that shortly.) However, PostgreSQL PITR allows and even encourages users to manipulate the logs to perform some very useful tasks:

* Creating a bit-for-bit backup of a server without halting
* Restoring a server to a specific point in time
* Creating a warm standby server

Mas:

http://scale-out-blog.blogspot.com/2009/02/simple-ha-with-postgresql-point-in-time.html