These tools are essential if you want to scale up deployment of servers, especially now that more services are being hosted on virtual servers, making deployment of the hardware, O/S, and application completely independent.
"One senior systems engineer at Digg.com was able to rebuild 60 [virtual] machines from scratch in two hours [using Puppet] that would have taken two full days of work if done manually. 'And I was largely a spectator,' said that engineer, Paul Lathrop, of Digg. 'Now that’s automation.' ”Puppet is not the only game in town, if you're interested in these tools, you also need to look at cfengine, isconf, and bcfg2. Interestingly enough, two of projects appear to use trac for release management. These are all open source projects, with various levels of commercial support. The commercial nova edition of cfengine, adds some extra features for a price.
The value of these tools is that they offer automatically enforced policies, with implicit reporting of any exceptions.
