PostgreSQL 9.0 allow you to have replicated hot standby servers which you can query and/or use for high availability.  While the main components of the feature are included with PostgreSQL, the user is expected to manage the high availability parts.  repmgr allows you to monitor and manage your replicated PostgreSQL databases as a single cluster.Source code for repmgr is available from github.  Release archive:

• V1.0.0, 2010-12-05
• V1.1.0-beta1, 2011-02-24
• V1.1.0, 2011-03-09

A mailing list/discussion forum to discuss repmgr is available at Google Groups.