Glossary

I raised this same question in another forum ("How do I..." in the course, "teachers using moodle" in facultyroom.org) and the answer is no, glossaries do not allow groups.  There is a technical reason for this having to do with slowing down the software too much - you can read all about it in the other forum. 

To accomplish something very similar to what you want to do, I have elected to have different groups create their own wikis (which do allow groups) in which they define terms or concepts.  It doesn't have the nice alphabetical search that a glossary does, but I came up with a main page that will serve as an index.  My plan hasn't met live students yet, so take this as a suggestion rather than  the voice of experience

Cheers!

Russ