There  is little case law on this subject--the interplay of social media and nonsolicitation agreements. At one extreme, a phone call or email directly to a former colleague about an opening would clearly be solicitation. At the other extreme, a newspaper, Monster, or Craigslist add about an opening, visible to the whole world, would not be solicitation. In between in Facebook: even if you did not aim it directly at this person, only your friends could view what you posted and if a subset of your friends are former colleages, it *might* be soliciation, since it might be directed "enough." You should not post anything about your new business in any forum where former colleagues can see it and probably should minimize contact with them and also keep that contact demonstrably not about work and "offline." Among other things, while you have a nonsolicitation in force, it might be best to not network with them--the line between networking and solicitation, if any do take job action based on the contact, is very thin.