Sorry about the lack of documentation for that portlet. It is scheduled to be fixed for the next release.
The quick summary, is that this is a sample implementation of the IRoleResolver API. In this implementation, it looks for the named attribute(s) of the user, and if found, assigns the user to that role. It will also specify default roles for all users.
I doubt whether this would exactly fit the needs of a solution in general, but it fit the needs of one customer and is used as an example.
Regards,
–mark
(PS: In our rush to get this example released, we accidentally left it in the distribution where it didn’t belong)