Voting on posts seems somewhat strange (also strange that it isn't integrated in the main page), but I may have different use cases in mind than you do. In fact, that would be a good thing to point out on the site, what do you have in mind for possible use cases?
My idea is that this would be shared by people who know each other in real life. Voting on a friend's contribution seems strange.
Another really cool feature would be the ability to share a network with simply a private URL, no need for other members to sign up if they don't want to. Each user can get their own private URL which ties them back to the email address they were invited on so you know who's who.
If you ever want to talk in more detail about this (like after the HN story falls into obscurity), feel free to contact me at the email address cryptically listed in my profile.
