I was also diagnosed at 17, few months from my 18th b-day. My parents were and still are very involved! I think especially because he could be going away to college soon (I don't know him obviously but....) he's on his way to being a young adult and soon will be "on his own". Its important for you to be involved but not on his case 24/7. Let him be with his friend and learn his new ways of doing the old things. And it is important for his friends to know his situation, more than likely his friends will be very interested.
Renka- I just got the Burnout book for xmas and I've heard a lot of good things about it....sounds like I need to read this asap!