I just created a git repository for django-apikey, which provides an API key-based authorization backend for use with django REST services. Currently, it works with django-piston, but I do plan on adding support for other django REST packages.
django-apikey was inspired by some posts on StackOverflow while trying to get django-piston’s OAuth functionality working.
It requires your application to not only use django.contrib.auth, but to also have user profiles set up. There’s a requirement for 2 methods to be added to your existing user profile model, but these can be left out with minimal loss of functionality.
I’ve used it on “regular” django installations, i.e. ones using a relational database. It also works in the Google AppEngine environment, as can be seen at my messaging app, Nq/Dq, where it provides the authorization for the REST api.