Just reread your blog post. I wonder if the answer is not about being careful simply with the people you choose to bring in your network. Maybe it's too hard: you choose to trust your immediate connections, but what about their connections? Is the friend of my friend my friend too?
You see that question on social sites where you can choose how far you wish to share your "privacy". Friends? Friends of friends? Everyone?
Another way is perhaps to have a dedicated setup, like the dedicated pizza boxes that google rent to customers. I know a guy who does something like that, he's got something offering a panel of functionalities similar to linkedin, but I don't know if that would correspond to what you're looking for.