We actually hacked something up along these lines as a demo for Copenhagen University.
We looked at the public portal, but decided against using it, because it would require the group admin to maintain two portals. Whenever he adds a portlet or rearranges things, he'd have to do the same add/rearrange to the non-member portal.
Instead, what we did was make some changes to the permission structure, so that portlets actually check permissions on the relevant packages before displaying themselves. That way, you'll only see what you're allowed to see.
Here are a few links for you to try it out:
If you simply visit
http://nik.collaboraid.net
you'll see a list of publicly accessible courses.
You can browse those (currently 'that') course, and see whatever the admin has allowed you to see.
Then if you login with the 'admin' link from this page:
http://nik.collaboraid.net/register/
you can visit:
http://nik.collaboraid.net/dotlrn/classes/computerscience/computerandnetworksecurity/computerandnetworksecurityfall20032004/public-access
(also linked off of the class admin page), where you can define the public access of the group with the checkboxes and the 'make public' and 'make private' buttons.
Try it out.
The code can be downloaded here:
http://www.collaboraid.biz/developer/nik-packages.tgz
It hasn't been committed because it's a hack. It's a hack because we had zero time to do it, and because .LRN permissions are a hack in the first place.
But please do take a look, and if someone has the time and courage to clean it up and commit it (the tarball also contains a number of other interesting new features, such as easy access to archived courses, anonymous forums postings, etc.), then please go ahead.
/Lars
