Those accounts comes with "@domain.com", and when I try to change their user rights with the special pages, I was given the error of "cannot edit uesr rights of other wiki".
Soon I found in the manual pages that I need to have the "userrights-interwiki" for my bureaucrat group, so I added that in my LocalSettings. Then I was given another error of "Database mydomain.com does not exist or is not local."
Any help~? I suggest not storing the username with the domain - since with this extension we are allowed to use google apps of only one domain - so with "@domain.com" doesn't really make much difference.