I had have the opportunity to manage coporate infrastructure few times. One of them with a client who has large network to manage along with bright fellows in that team.
Configuring system and distribute to the same configuration to different node is a error prone and cumbersome job for the system administrators.The rescue act has been done by the little piece of software called "Puppet".
Most of the big corporation started to implementing this software in their network or system administrator get adhere to it ,just to make their life little easier and painless.
Yes,it is written a small but extremely powerful and ease of use interpreted language called "ruby",please visit this site http://www.ruby-language.org.So one has to have little bit of familarity with it handle it properly.But there is no hard and fst rule to learn it or know it in leangth and breadth ( although no harm in doing so!! ).
Say for example; if you want a particular configuration file to be updated across several hundred or thousand of node at once within very very limited timeframe,it is the software to watch out.One has to just write once the configuaration file once on master server and start the daemon .Client or nodes started to get it from the master.
Yes ,essentially the underlying architecture is a client/server model.So the master server can also implement the client too to manage itself,often the case.
For more details on that subject please visit http://reductivelabs.com and go through the document ,as it is very well describe it's job.
The bottom line is that it's become a swiss army knife for the system administrator to handle large network.
PS: I am using it for quite a while now personally,and enjoy the power it delivers.ReductiveLabs is earning hell lot of money to lend it to the big corporates.