PyMongo vs MongoEngine for Django
I assume you have not read the MongoEngine claim.

MongoEngine is a Document-Object
  Mapper (think ORM, but for document
  databases) for working with MongoDB
  from Python.

This basically say it all.
In addition: your claim that Pymongo would deliver objects is wrong....well in Python everything is an object - even a dict is an object...so you are true but not in the sense of having a custom class defined on the application level.
PyMongo is the low-level driver wrapping the MongoDB API into Python and delivering JSON in and out. 
MongoEngine or other layers like MongoKit map your MongoDB-based data to objects similar to native Python database drivers + SQLAlchemy as ORM.
For one of my projects I prefered using Django+Mongo.
Why should I use MongoEngine, but not just PyMongo? What are advantages? Querying with PyMongo gives results that are allready objects, aren't they? So what is the purpose of MongoEngine?