Likely, the most popular one are puppet and chef. Puppet is written in Ruby where Chef is in Ruby and Erlang (the newest version).
Is there any automation and configuration framework that is natively written in Python.
Analisis and results description
Automation tool called Salt or Saltstack is written in Python and provide a native support for modules written in Python.
The tool is rapidly evolving and getting popular. On the main project page we can find number of resources like email group, wiki and IRC (http://saltstack.com/community). There is even a YouTube channel. Below is an introduction and example how salt works.