Use Esri Geoservices REST as backend for Python web framework (Django?)

It's entirely possible, but nobody's done it yet. Arc2Earth uses an independent implementation of the Esri REST API to host on Google App Engine. And implementing the REST API makes it possible to do things like expose geoprocessing services and feature layers for analysis in ArcGIS Explorer.

It's harder than it sounds. Django Models are, at the moment, pretty tied to a SQL database world and the Admin is, in turn, pretty tied to Django models.

Your best bet is probably to look at something like Django-nonrel

http://www.allbuttonspressed.com/projects/django-nonrel

the Esri REST api does not expose any table/layer admin functions, so you can't really use it for adding/changing/deleting maps or layer schema. It does allow for CRUD on features within each table though.

so, I could see frontending an individual featurelayer via GeoDjango (using the featurelayer as a "table") but you would only be able to query and edit the features within the table (not its schema)

moving forward with their hosted solution on ArcGIS.com, it's still unclear if they will allow for REST access to admin functionality. For instance, most of the demos they've been showing of drag/drop shapefile/csv mapping don't actually create any FeatureLayers, they are added as individual features to the map's json (kinda like a more functional graphics layer). Hopefully if they do add schema admin functionality, the Geospatial REST spec will be updated as well.

cheers brian