Google Groups will be revamping soon, dropping its vestigial wiki-like functions and concentrating on forum, email distribution, and group sharing core. It should be expected that the interface would change in concert and the preview is now available. That said, the new interface is still bare bones and lacks the tight integration with GMail and Google Docs that would make it a useful destination for Enterprise collaboration. One thing that is still missing is a way to easily form nested groups – a prerequisite for modeling most organizational structures.
The Google Apps Blog (original posts): Preview the new Google Groups
Millions of people around the world use Google Groups to power discussions with the groups and communities they care about. We have been working hard to improve this experience, and today we are happy to announce a sneak preview of the brand new Google Groups.