Quick update: Florian Hahn has implemented a solution for permission handling with Django on non-relational databases. Django's own permission system unfortunately requires JOIN support and thus doesn't work. After his original announcement the code has been optimized, so a permission check can be done with just two database operations. Also, his backend now scales with the number of users. Florian has posted installation and usage instructions on his blog. Check it out if you need permission support in your project.