I think it should be kept separate.  But I think we should do the baby steps now.

Why not just change the text at /acs-admin from "ACS Administration is used to administer the site-wide services of the ArsDigita Community System." to "OpenACS Administration is used to administer the site-wide services".

Then on /admin just place a text on top of the page "[subsite name] Administration is used to administer the subsite services".

Small changes but that should help new users... that there is a differenct between the 2 of of them.  Or why don't we just rename "OpenACS Administration" to "Site-Wide Administration".