What does Group Admin permit

When adding users to groups, you have the ability to checkbox them to be a group admin. What benefit does this allow the user? I know they are not able to log into the web based interface to do any admin work on the group, but does this allow them to add / remove members from the group another way?

no, it does not. At the moment, we don’'t expose any services that use that flag. However, we do plan on offering things that will use it in the not too distant future

There are already JEPs, XEPs about this kind of functionality that could be implemented.