How do you feel about talking candidly with moms or dads you don't know regarding your marriage problems or family struggles? Is it liberating and therapeutic or do you feel a twinge of guilt?
I think it all depends upon how anonymous you are in your community - i.e. if you have personal friends within the same community or people within your locality that know you both - NOT a good idea. But if you are simply an "i-net" personality (someone the members will only see within the network) then it's fine.
We all have boundaries and I'm pretty certain no-one is going to dish the dirt on their partners dirty habits, sexual preferences or air the stuff of marriage breakups but social networks can be a great place to find support and help when you feel you have nowhere else to turn to.
Personally when I was pregnant and living by myself in London with no family or friends nearby for support I found a lot of support from social networks. My boyfriend was working away at the time and he understood that it was hard on me being a pregnant mum on her own in a very big city. I made some great friends through the networks I belong to and I would always tell him about who my new friends were and what advice they'd given me.