I have watched the tutorial explaining how to set up the Site Groups feature in the PE edition of DNN 6.1.  However, I am unclear as to what Site Groups actually allows you to do.  My questions:

1.  Is Site Groups limited to only allowing a single sign on and editing of permissions for users across mutliple portals?

2.  Does use of Site Groups require all of my domains to be setup under the same root domain name? I think it does.

 3.  Does Site Groups allow for sharing of user profile fields across portals?  For example, if a user updates his/her postal code in one portal, does it update that information across all of the portals in the Site Group?

4.  If I go to Admin, Site Settings, User Account Settings, Profile Settings, and update or add a new profile property, does it exist within both portals?

Thank you for taking the time to answer my questions.  Of course, if there is something you can refer me to so I can learn more about the Site Groups feature, I would appreciate it.

Jim