I am writing a fogbugz wiki plugin that needs to request a list of cases for groups of users.
This is a little tough with the Fogbugz Database API since there is no way to build OR type where clauses yet.
So I had the idea that the PermissionGroups could be reused to get this.
It turns out that our usage for a team is both real users and one or two virtual users depending on the workflow for the project.
I even managed to add a virtual user to the PermissionGroupMemeber table manually in SQL so it appears to work and not really interfere with anything.
Its just the Group Editor screen that prevents you from adding virtual users to groups.