What Google Says:
This is part of Google Apps For Business. If you enable the optional Google Groups for Business service, you can enhance messaging and collaboration among your users.
Source: Google Quickoffice
Why You Should Use It:
This service has great advantages for business and educational institution users. Business users could easily create groups to interact even more quickly with their departments, groups, task forces, and special-interest groups. Customer service, support, and sales depts could each create teams that people outside your company could send messages to.
In academic institutions, instructors can boost communications among students by creating teams for their classes, subjects, and grade levels. Pupils could use teams to reach other pupils in their classes, sports teams, clubs, and after-school activities.
Administrators still retain full control over the groups and can completely control how users use groups to create interactions.