PostgreSQL Database Clustering

For live database clustering refer to the following

1. Slony

This is a master-slave database replication system, mainly for fail over and back up purposes.

http://www.slony.info/

2. Continuent

This clustering software is targeted at achieving High Availability and Scalability

http://www.continuent.com/index.php?option=com_content&task=view&id=212&Itemid=169