app-engine-patch currently has the most of django functional, including sessions, contrib.auth, sites, and some other standard django apps. However, its main drawback (my opinion) is that it uses a zip file of a modified version of django to achieve this functionality and the current maintainers don't seem to have kept pace with current django releases. Currently it seems to be the consensus of the past and present maintainers that this approach is too cumbersome to maintain and therefore no one is currently maintaining it.
google-app-engine-django, uses a monkey patch approach of the latest django version included in the production GAE runtime, so as long as google continues to track django releases you'll be kept up to date regarding django. However, it currently has not fully ported contrib.auth, so you can only authenticate with google accounts - which can be a big drawback depending on whether you want contrib.auth User models to work as you know them on sql backends. There is also no django admin support in the helper as there is in app-engine-patch. A fork of django-app-engine-django exists which adds in some of the contrib apps, such as flatpages, sites, and sitemaps. Also note, it only works on django versions up to 1.1, until issue #3230 Django 1.2 is added to use_library, unless you upload django as a zip file.
On the horizon, the original developer of app-engine-patch has been working on the django-nonrel branch, but this may be pretty far away from being included in a django release. This django developers thread has a lot of information about these efforts.
Separately, there is a google summer of code project working on integrating some aspects of nonrel db's.