Is it possible to create an end-user facing site using Django admin alone?
As for row-level permissions in the admin, in the SVN version of Django you can override the has_add_permission, has_change_permission, and has_delete_permission methods on the ModelAdmin object to implement the custom permissions logic yourself in a way that will apply across the entire admin. I'm pretty sure this feature is going to be in the 1.2 release this year. It doesn't seem to be in the documentation yet, but if you can find the default methods in the django/contrib/admin/options.py file of the Django source, exact instructions are in the docstrings.
I wouldn't recommend doing the entire app in the admin, though. It would work fine for the parts of the app where people are writing their posts and creating their blogs, but the admin wouldn't be suited for just displaying the data, unless you write lots of custom code. Writing views that can display objects and submit comments in Django isn't very hard - most of the work is in the templates.
I'm very new to Django, having never developed on it. 
I'm trying to develop a site which has functionality exposed only to authenticated users (typical enterprise thing: for this discussion, let's say it's a private blogging platform). 
The functionality I'm looking for is:

Users can create a new blog.
each user can belong to multiple groups: the user can only view/comment on blogposts created by member of groups (s)he belongs to.
Each user can modify/delete only the posts (s)he creates.

As I see it, this is essentially a CRUD application with access control, and the admin app seems to have a lot of this functionality builtin. Is it feasible to develop this complete application using the admin application alone (not as a prototype, as a release-quality solution), or should I look beyond (Generic views? ModelForms?)
I'm trying to estimate how long this will take (learning + implementation), so your feedback could give me a good idea, in addition to teaching me the ways of this new Django-world :)
Edit: specifically, one of my worries is per-object/per-row permissions. The django wiki says the Permissions system doesn't support that, so can I still use the admin app?