Mongodj is a project mainly written in Python, it's free.
mongo driver for django
MongoDB backend for Django.
The aim of the project is to create a native django DB backend for mongo (so that it can be accessed through the django ORM).
The project is in the very early stage
mongoDB is accessed through pyMongo.
It relies on the django-nonrel branch: http://bitbucket.org/wkornewald/django-nonrel/wiki/Home