TimeMachine is a change tracking, auditing, and revision control system for Postgresql databases. Timemachine allows all changes to tables in a postgresql database to be tracked, and allows recreation of tables as they existed at specific points in time.
The TimeMachineproject is a PostgreSQL Community project that is a part of the pgFoundry.
The pgFoundry page for the project is at http://pgfoundry.org/projects/timemachine, where you can find downloads, documentation, bug reports, mailing lists, and a whole lot more.