http://admin.webapp.con

Hey everyone! I just finished through Simply Rails 2 and after looking around a bit I've decided I want my admin panal laid out like the subject line. My question is once an app gets moved to a subdomain don't you lose allot of privledges/permissions on the main app? Is there an example around I might be able to look over to better understand how this works? I feel at the moment I just don't get how the two communicate.

Thanks -bp