3
Short answer, nope.
I have not seen any Active Directory plugins which would allow you to use AD as a user dB. You may try and find / create a method to link your AD to LDAP and use the XOOPS LDAP authentication option (thinking AD=>LDAP would be easiest to find pre-existing).
Depending on your needs, you could try to use Duplicatable Modules (Pical, TinyD, etc) and assign unique group permissions to each duplicated install.
Aside from that, you can find a module that will bring any member of a specific group (at login) to a unique page based on their group (cant remember the name of it now). If you set up your groups by Dept you could show each group/Dept. unique content.
GL