Do what you feel, we do all pass one day. I tried making a sobriety facebook page, but ended up using a little over a week later.. I support you!
I think it wouldn't make a difference if you just told people who you are in contact every day rather than a full bodied facebook post. I'm coming down off my facebook/twitter addiction of telling them everything. Sticking to like minded company in general more nowadays. While it is I feel a duty of mines to spread the knowledge of god, and realizing sobriety is apart of that. I'd say decide for your self and then learn what works best for you!