Topic: Making multigroup a native feature
For regular members, the most useful thing about usergroup is to be able to say: "these members can read this private forum, these others can read this other forum" and so on.
But right now, someone can't be in two groups, and more problematic someone can't be in a usegroup and have a forum function (like being a moderator).
I really, really think a multigroup feature is not a gadget.
I know there are some issues with permissions overall, but with global scheme (like if you are authorized once, you are authorized even if one of your usergroup is not) it should be easy to deal with.