The current style of permission group allows an administrator to assign a user to it and also assign posting and comment rights to certain sections of articles. So, if I'm an 'Editor' and editors are allowed to alter 'News' stories, I can alter all such stories.
There is another type of group, though, where the user's membership is dynamic. Imagine a group named 'Submitter'. If I pulled up an article I wrote, I would temporarily belong to 'Submitter'. If I pulled up an article written by someone else, I would not belong to the group. This example could be coded in a more direct fashion by checking user nicknames, but there are others where this won't work. Imagine one called 'Assignee.' When a user first writes an article, they could enter a list of other users allowed to fill the 'Assignee' role. A single field with a comma separated list of nicknames would do the trick, I think.
With permission groups like this (and possibly others) an administrator could create sections that permit people to edit their own work or create access lists to delineate their collaborators. Such a section could then act as a draft area where submitters and their assignees could work together on a single article. This would truly put 'collaborative' into our collaborative media.
This would put users into more than one permission group. I don't know the Scoop code base well enough to know if this is a problem or not. Their permission list would also be dynamic, so it would have to be checked when actions are attempted, but I imagine that is already the case.
