It depends on exactly what you what to get out of a policy management tool. The market for these sorts of products, both open source and proprietary, is not 100% mature. In the open source world, the best tools for this are probably cfengine and Puppet. These both allow the management and configuration of remote hosts and the capability to remotely detect and remediate deviation from a configuration standard, policy or Standard Operating Environment (SOE).
This was first published in March 2007