I think this is pretty individual probably.
Amost everyone i know knows i am an alchoholic/addict. well....some people professionally don't know...but even my professional contacts that i've known for years are aware.
I suppose there is an up side and a down side to people knowing, but in the end it's a whole lot easier to get on with my sobriety if i'm not having to avoid and slide over the fact that i'm dealing with this disease.
I remember with my alchoholism/addiction and with another large issue in my life...when i finally told friends and family what the issue was...they were so realieved...the common response was "well that explains a lot".
but you can't take it back once you tell so I think some considertion as to what is the best action for everyone about this is definatly a good idea...what is best for them as well (not short term but long term best )